Pharma Flashcards
Phase I reactions:
oxidation, reduction, and hydrolysis. Mainly performed by the P450 enzymes but some drugs are metabolised by specific enzymes, for example alcohol dehydrogenase and
xanthine oxidase. Products of phase I reactions are typically more active and potentially toxic
Phase II reactions:
conjugation. Products are typically inactive and excreted in urine or bile.
Glucuronyl, acetyl, methyl, sulphate and other groups are typically involved.
* The majority of phase I and phase II reactions take place in the liver.
First-Pass Metabolism
concentration of a drug is greatly ↓ before it reaches the systemic circulation due to hepatic metabolism. As a consequence much larger doses are need orally than if given by other routes. This effect is seen in many drugs, including:
* Aspirin
* Isosorbide dinitrate
* Glyceryl trinitrate
* Lignocaine
* Propranolol
* V erapamil
Zero-Order Kinetics
describes metabolism which is independent of the concentration of the reactant. This is due to metabolic pathways becoming saturated resulting in a constant amount of drug being eliminated per unit time. This explains why people may fail a breathalyser test in the morning if they have been drinking the night before
Drugs exhibiting zero-order kinetics * Phenytoin
* Salicylates * Heparin
* Ethanol
Drugs exhibiting zero-order kinetics *
Phenytoin
* Salicylates * Heparin
* Ethanol
Drugs affected by acetylator status:
- Isoniazid
- Procainamide * Hydralazine * Dapsone
- Sulfasalazine
P-450 Dependent Drugs WEPTD:
- Warfarin
- Estrogen
- Phenytoin
- Theophylline
- Digoxin
P450 inhibtors: (causing low metabolism of WEPTD → Toxicity)
Acute alcohol intake
* Allopurinol
* Amiodarone
* Cimetidine, omeprazole
* Dapsone
* Imidazoles: ketoconazole, fluconazole
* INH
* Macrolides (Azithro-Clarithro-Erythro mycins)
* Quinolones (ciprofloxacin)
* Quinupristin
* Sodium valproate
* Spironolactones
* SSRIs: fluoxetine, sertraline
* Grapefruit juice (potent inhibitor of the cytochrome P450 enzyme CYP3A4)
* Protease inhibitors (ndinavir, nelfinavir, ritonavir, saquinavir)
P450 inducers:
- Antiepileptics: phenytoin, carbamazepine (note that valporate is an inhibitor)
- Barbiturates
- Chronic alcohol intake
- Griseofulvin
- Quinidine
- Rifampicin
- Smoking (affects CYP1A2, reason why smokers require more aminophylline)
- St John’s Wort
- Sulfa drugs
- Tetracycline
- Nevirapine (NNRTI)
Drugs that can be cleared with Hemodialysis
Barbiturate
* Lithium
* Alcohol (inc methanol, ethylene glycol)
* Salicylates
* Theophyllines (charcoal hemoperfusion is
preferable)
Drugs which cannot be cleared with HD include
Tricyclics
* Benzodiazepines (diazepam,midazolam,alprazolam)
* Dextropropoxyphene (co-proxamol)
* Digoxin, β-blockers
Drugs to avoid in Renal Failure
- Antibiotics: tetracycline, nitrofurantoin
- NSAIDS
- Lithium
Drugs likely to accumulate in renal failure - need dose adjustment
Most antibiotics including penicillins, cephalosporins, vancomycin, gentamicin, streptomycin
* Digoxin, atenolol
* Methotrexate
* Sulphonylureas
* Furosemide
* Opioids
Drugs relatively safe in renal failure - use in normal dose
Antibiotics: erythromycin, rifampicin
* Diazepam
* W arfarin
Drug Induced Impaired Glucose Tolerance
Thiazides, furosemide (less common)
* Steroids
* Tacrolimus, cyclosporin
* Interferon-α
* Nicotinic acid (vitamin B3)
β-blockers cause a slight impairment of glucose tolerance. They should also be used with caution in
diabetics as they can interfere with the metabolic and autonomic responses to hypoglycemia
drugs Hepatocellular Picture
- Alcohol
- Amiodarone
- Anti-tuberculosis: isoniazid,
rifampicin, pyrazinamide - Halothane
- MAOIs
- Methyldopa
- Paracetamol
- Sodium valproate, phenytoin
- Statins
drugs Cholestasis (+/- Hepatitis)
Anabolic steroids, testosterones
* Antibiotics: flucloxacillin, co-amoxiclav,
erythromycin*, nitrofurantoin
* Fibrates
* Oral contraceptive pill
* Phenothiazines:
prochlorperazine
* Rarely: nifedipine
* Sulphonylureas
drugs Liver Cirrhosis
Amiodarone * Methotrexate * Methyldopa
Drugs Causing Visual Disturbance:
Cataracts
* Steroids
Corneal opacities
* Amiodarone * Indomethacin
Optic neuritis
* Ethambutol
* Amiodarone
* Metronidazole
Retinopathy
* Chloroquine, quinine Blue tinge in vision:
* Sildinafil Yellow-green tinge:
* Digoxin
Drugs Causing Gingival hyperplasia
- Phenytoin
- Cyclosporin
- Calcium channel blockers (especially nifedipine)
Other causes of gingival hyperplasia include - Acute myeloid leukemia (myelomonocytic and monocytic types)
Drugs Causing Urticaria:
- Aspirin
- Penicillins * NSAIDs
- Opiates
Drugs Causing Acute Intermittent Porphyria (AIP)
- Alcohol
- Barbiturates
- Benzodiazepines
- Halothane
- Oral contraceptive pill
- Sulphonamides
Acute Intermittent Porphyria (AIP) safe drugs
- Paracetamol * Aspirin
- Codeine
- Morphine
- Chlorpromazine * β-blockers
- Penicillin
- Metformin
Drug Induced Thrombocytopenia (probable immune mediated)
- Heparin
- Abciximab
- NSAIDs; ASA
- Diuretics: furosemide
- Quinine
- Antibiotics: penicillins, sulphonamides, rifampicin
- Anticonvulsants: carbamazepine, valproate
Drug Induced Pancytopenia:
- Cytotoxics
- Antibiotics: trimethoprim, chloramphenicol
- Anti-rheumatoid: gold (sodium aurothiomalate), penicillamine
- Carbimazole*
- Anti-epileptics: carbamazepine
- Sulphonylureas: tolbutamide
Drug Induced Photosensitivity:
- Thiazides
- Tetracyclines, sulphonamides, ciprofloxacin
- Amiodarone
- NSAIDs e.g. Piroxicam
- Psoralens
- Sulphonylureas
Nicotine replacement therapy
Adverse effects nausea &
include vomiting, flu-like
headaches
and
symptoms
* Nice recommend offering a
combination of nicotine patches and another form of NRT (such as gum, inhalator, lozenge or nasal spray) to people who show a high level of dependence on nicotine or who have found single forms of NRT inadequate in the past
Nicotinic receptor partial agonist Varenicline
- Should be started 1 week before the patien target date to stop
- The recommended course of is 12 weeks (but patients should be monitored regularly and treatment only continued if not smoking)
- Has been shown in studies to
be more effective than bupropion - Nausea is the most common adverse effect. Other include headache, insomnia, abnormal dreams
- V arenicline should be used with caution in patients with a history of depression or self-harm.
- Contraindicated in pregnancy and breast feeding
Norepinephrine and dopamine reuptake inhibitor, and nicotinic antagonist Bupropion
- Should be started 1 to 2 weeks before target date.
- Small risk of seizures (1: 1,000)
- Bupropion should not be prescribed to individuals with epilepsy or other conditions
that lower the seizure threshold, such as alcohol or benzodiazepine withdrawal, anorexia nervosa, bulimia, or active brain tumors. It should be avoided in individuals who are also taking MAOIs. When switching from MAOIs to bupropion, it is important to include a washout period of 2 weeks. Also pregnancy and breastfeeding are contraindications.
Salicylate Overdose:
mixed respiratory alkalosis and metabolic acidosis
sweaty, confused patient
pulmonary edema suggests severe poisoning and
is an indication for hemodialysis
Indications for hemodialysis in salicylate overdose
- Serum concentration > 700mg/L
- Metabolic acidosis resistant to treatment
- Acute renal failure
- Pulmonary edema
- Seizures
- Coma
Paracetamol Overdose:
Management:
* Start N-acetyl cysteine immediately
* Naloxone if there is hypoxia or respiratory depression
King’s College Hospital criteria for liver transplantation (paracetamol liver failure) Arterial pH < 7.3, 24 hours after ingestion OR all of the following:
- Prothrombin time > 100 seconds
- Creatinine > 300 μmol/l
- Grade III or IV encephalopathy
The following patients are at ↑ risk of developing hepatotoxicity following a paracetamol overdose:
- Chronic alcohol excess
- Patients on p450 enzyme inducers (rifampicin, phenytoin, carbamazepine)
- anorexia nervosa: ↓ glutathione stores
- HI
Digoxin Toxicity:
Actions
* ↓ conduction through the atrioventricular node which slows the ventricular rate in atrial fibrillation and flutter
* ↑ the force of cardiac muscle contraction due to inhibition of the Na+/K+ ATPase pump
Features
* Generally unwell, lethargy, nausea & vomiting, confusion,
* Arrhythmias (e.g. AV block, bradycardia)
Precipitating factors Digoxin Toxicity:
- Classically: Hypokalemia*
- Myocardial ischemia
- Hypomagnesemia, acidosis (Hypo pH), Hypercalcemia, Hypernatremia
- Hypoalbuminemia
- Hypothermia
- Hypothyroidism
- Drugs: amiodarone, quinidine, verapamil, spironolactone (compete for
secretion in distal convoluted tubule therefore ↓ excretion)
Digoxin Toxicity: management
Management
* Digibind
* Correct arrhythmias
* Monitor K+
Indications for administration of Digoxin specific Fab Fragment are:
- Hemodynamic instability
- Life-threatening arrhythmias
- Serum potassium >5 mmol/l in acute toxicity
- Plasma digoxin level >13nmol/l
- Ingestion of more than 10 mg digoxin in adults and 4 mg in children
Cyanide
Presentation
* ‘Classical’ features: BRICK-RED SKIN, smell of bitter almonds
* Acute: hypoxia, hypotension, headache, confusion
* Chronic: ataxia, peripheral neuropathy, dermatitis
Management
* Supportive measures: 100% oxygen
* Definitive: IV dicobalt edetate
Ethylene glycol toxicity management -
fomepizole. Also ethanol / hemodialysis
Ethylene glycol - Features of toxicity are divided into 3 stages:
Features of toxicity are divided into 3 stages:
* Stage 1: symptoms similar to alcohol intoxication: confusion, slurred speech, dizziness
* Stage 2: metabolic acidosis with high anion gap and high osmolar gap. Also tachycardia,
hypertension
* Stage 3: acute renal failure
Cocaine heart
- Myocardial infarction
- Both tachycardia and bradycardia may occur
- Hypertension
- QRS widening and QT prolongation
- Aortic dissection
Cocaine neuro impact
Neurological effects
* Seizures
* Hypertonia
* Hyperreflexia
Ecstasy overdose features
Clinical features
* Neurological: agitation, anxiety, confusion, ataxia
* Cardiovascular: tachycardia, hypertension
* Water intoxication
* Hyperthermia
* Rhabdomyolysis
* Hyponatremia
Ecstasy treatment
Management
* Supportive
* Dantrolene may be used for hyperthermia if simple measures fail
Mercury Poisoning:
Features
- Paraesthesia
- Visual field defects
- Hearing loss
- Irritability
- Renal tubular acidosis
chelation therapy for acute inorganic mercury poisoning
2,3-dimercapto-1- propanesulfonic acid (DMPS), D- penicillamine (DPCN), or dimercaprol (BAL). Only DMSA is FDA-approved for use in children for treating mercury poisoning.
no clear clinical benefit from DMSA treatment for poisoning due to mercury vapor.
Lead Poisoning features
abdominal pain and neurological signs
Features
* Abdominal pain
* Peripheral neuropathy (mainly motor)
* Fatigue
* Constipation
* Blue lines on gum margin (only 20% of adult patients, very rare in children)
Lead Poisoning investigations
Microcytic anemia
* Blood film shows red cell
abnormalities including basophilic stippling and clover- leaf morphology
* Raised serum and urine levels of delta aminolaevulinic acid may be seen making it sometimes difficult to differentiate from acute intermittent porphyria
* Urinary coproporphyrin is also ↑ (urinary porphobilinogen and uroporphyrin levels are normal to slightly
Lead Poisoning Management
Dimercaptosuccinic acid (DMSA)
* D-penicillamine
* EDT A (EthyleneDiamineTetraAcetic acid)
* Dimercapro
Carbon Monoxide
Confusion, pyrexia and pink mucosae are typical features of carbon monoxide poisoning
Management
* 100% oxygen
* Hyperbaric oxyge
Indications for hyperbaric oxygen
- Loss of consciousness at any point
- Neurological signs other than headache
- Myocardial ischemia or arrhythmia * Pregnancy
Oculogyric Crisis features
dystonic reaction to certain drugs or medical conditions
Features (extra pyramidal)
* Restlessness, agitation
* Involuntary upward deviation of the eyes
Causes- Oculogyric Crisis
Phenothiazines
* Haloperidol
* Metoclopramide
* Postencephalitic Parkinson’ s disease.
Oculogyric Crisis
Treatment
* Procyclidine * Benztropine
Contraindicated in pregnancy antibiotics
Tetracyclines
* Aminoglycosides
* Sulphonamides
* Trimethoprim
* Quinolones: the BNF advises to avoid due
to arthropathy in some animal studies
drugs CI in preggo
ACE inhibitors, ARBs
* Statins
* W arfarin
* Sulfonylureas
* Retinoids (including topical)
* Cytotoxic agents
Breastfeeding Contraindications:
Antibiotics: ciprofloxacin, tetracycline, chloramphenicol, sulphonamides
* Psychiatric drugs: lithium, benzodiazepines, clozapine
* Aspirin
* Carbimazole
* Sulphonylureas
* Cytotoxic drugs
* Amiodarone
safe in breastfeeding
Antibiotics: penicillins, cephalosporins, trimethoprim
* Endocrine: glucocorticoids (avoid high doses), levothyroxine*
* Epilepsy: sodium valproate, carbamazepine
* Asthma: salbutamol, theophyllines
* Psychiatric drugs: tricyclic antidepressants,
antipsychotics**
* Hypertension: β-blockers, hydralazine,
methyldopa
* Anticoagulants: warfarin, heparin
* Digoxin
Standard Heparin mOA and monitoring
Activates antithrombin III forms a complex that inhibits Xa, IXa, XIa and XIIa
Activated partial thromboplastin Anti-Factor Xa (although routine time (APTT)
LMWH) MOA
Activates antithrombin III forms a complex that inhibits Xa,
monitored with Xa
Heparin-induced thrombocytopaenia (HIT)
- Immune mediated - antibodies form which cause the activation of platelets
- Usually does not develop until after 5-10 days of treatment
- Despite being associated with low platelets HIT is actually a prothrombotic condition
- Features include a greater than 50% reduction in platelets, thrombosis and skin allergy
- Treatment options include alternative anticoagulants such as lepirudin and danaparoid
drenaline induced ischemia
phentolamine
Phenytoin monitoring
Trough levels immediately before dose
Cyclosporin monitoring
Trough levels immediately before dose
Digoxin monitoring
Digoxin
* At least 6 hrs post-dose
Lithium range
Lithium
* Range = 0.4 - 1.0 mmol/l
* Take 12 hrs post-dose
Botulinum Toxin (‘Botox’) indications
- Blepharospasm
- Hemifacial spasm
- Focal spasticity including cerebral palsy patients, hand and wrist disability associated with
stroke - Spasmodic torticollis
- Severe hyperhidrosis of the axillae
- Achalasia
Isotretinoin adverse effects
dverse effects
* Teratogenicity: ♀s MUST be using two forms of contraception (e.g. COCP and condoms)
* Dry skin, eyes and lips: the most common side-effect of isotretinoin
* Low mood, depression
* Raised triglycerides
* Hair thinning
* Nose bleeds (caused by dryness of the nasal mucosa)
* Benign intracranial hypertension: isotretinoin treatment should not be combined with
tetracyclines for this reason
Conversion between opioids
Oral codeine Oral morphine Divide by 10
Oral tramadol Oral morphine Divide by 5
Oral morphine Oral oxycodone Divide by 2
Oral morphine
To
Subcutaneous diamorphine Divide by 3
Oral oxycodone
Subcutaneous diamorphine Divide by 1.5
Hydrocortisone Equivalence
1mg prednisolone = 4mg hydrocortisone
* 1mg dexamethasone = 7mg prednisolone
Chemotherapy Side effects
- Anxiety
- Age less than 50 years old
- Concurrent use of opioids
- The type of chemotherapy used
metoclopramide in cancer
For patients at low-risk of symptoms then drugs such as metoclopramide may be used first-line. For high-risk patients then 5HT3 receptor antagonists such as ondansetron are often effective, especially if combined with dexamethasone
Doxazosin
α-1 adrenoceptor antagonist used in the treatment of hypertension and benign
prostatic hypertrophy
Lithium MOA
Mechanism of action - not fully understood, two theories:
* Interferes with inositol triphosphate formation
* Interferes with cAMP formation
Lithium Adverse effects
Adverse effects
* Nausea/vomiting, diarrhea
* Fine tremor
* Polyuria
* Thyroid enlargement, may lead to hypothyroidism
* ECG: T wave flattening/inversion
* W eight gain
Monitoring of patients on lithium therapy
Inadequate monitoring of patients taking lithium is common - NICE and the National Patient
Safety Agency (NPSA) have issued guidance to try and address this. As a result it is often an
exam hot topic
* Lithium blood level should ‘normally’ be checked every 3 months. Levels should be taken 12
hours post-dose
* Thyroid and renal function should be checked every 6 months
* Patients should be issued with an information booklet, alert card and record book
lithium tax precipitated by
precipitated by dehydration, renal failure, diuretics
(Especially bendroflumethiazide) or ACE inhibitors and ARBs
lithium tox features
Features of toxicity
* Coarse tremor (a fine tremor is seen in therapeutic levels)
* Acute confusion
* Seizure
* Coma
lithium tox treatment
anagement
* Mild-moderate toxicity may respond to volume resuscitation with normal saline
* Hemodialysis may be needed in severe toxicity
* Sodium bicarbonate is sometimes used but there is limited evidence to support this. By
increasing the alkalinity of the urine it promotes lithium excretion.
Tricyclic Overdose Features of severe poisoning include:
Features of severe poisoning include:
* Arrhythmias
* Seizures
* Metabolic acidosis
* Coma
Tricyclic Overdose ECG changes include:
- Sinus tachycardia
- Widening of QRS
- Prolongation of QT interval
phenytoin se chronic
Chronic
* Common: gingival hyperplasia, hirsuitism, coarsening of facial features
* Megaloblastic anemia (secondary to altered folate metabolism)
* Peripheral neuropathy
* Enhanced vitamin D metabolism causing osteomalacia
* Lymphadenopathy
* Dyskinesia
Sodium Valproate MOA
management epilepsy and is first line therapy for generalised
seizures. It works by increasing GABA activity
Sodium Valproate Adverse effects
Adverse effects
* Gastrointestinal: nausea
* ↑ appetite and weight gain
* Alopecia: regrowth may be curly (note that phenytoin → hirsutism while valporate → alopecia)
* Ataxia
* Tremor
* Hepatitis (also with phenytoin)
* Pancreatitis
* Teratogenic
Anticholinesterase Effects overdsose Features
Features can be predicted by the accumulation of acetylcholine (mnemonic = SLUD)
* Salivation
* Lacrimation
* Urination
* Defecation
* Cardiovascular: hypotension, bradycardia
* Also: small pupils, muscle fasciculation
Anticholinesterase OD managment
Management
* Atropine
* The role of pralidoxime is still unclear - meta-analyses to date have failed to show any clear
benefit
St John’s Wort
- Shown to be as effective as tricyclic antidepressants in the treatment of mild-moderate
depression - Mechanism: thought to be similar to SSRIS (although noradrenaline uptake inhibition has also
been demonstrated) - NICE advise ‘may be of benefit in mild or moderate depression, but its use should not be
prescribed or advised because of uncertainty about appropriate doses, variation in the nature of preparations, and potential serious interactions with other drugs’
Adverse effects - Profile in trials similar to placebo
- Can cause serotonin syndrome
- Inducer of P450 system, therefore ↓ levels of drugs such as warfarin, Cyclosporin. The
effectiveness of the combined oral contraceptive pill may also be ↓
Non-selective monoamine oxidase inhibitors
- E.g. tranylcypromine, phenelzine
- Used in the treatment of depression and other psychiatric disorder
- Not used frequently due to side-effects
Adverse effects of non-selective monoamine oxidase inhibitors
Hypertensive crisis: MAOIs reacting with tyramine containing foods e.g. Cheese, pickled
herring, Bovril, oxo, marmite, broad beans, liver, wine.
* Anticholinergic effects
Serotonin Receptors Agonists
- Sumatriptan is a 5-HT1D receptor agonist which is used in the acute treatment of migraine
- Ergotamine is a partial agonist of 5-HT1 receptors
Serotonin Receptors Antagonists
- Pizotifen is a 5-HT2 receptor antagonist used in the prophylaxis of migraine attacks.
- Methysergide is another antagonist of the 5-HT2 receptor but is rarely used due to the risk of
retroperitoneal fibrosis - Cyproheptadine is a 5-HT2 receptor antagonist which is used to control diarrhea in patients with carcinoid syndrome
- Olanzapine is 5-HT2 antagonist and D2 dopamin receptor blocker, it’s an atypical antipsychotic
- Ondansetron and Granisetron are 5-HT3 receptor antagonist and is used as an antiemetic… They
cause conistipation, dizziness and headache.
Triptans
are specific 5-HT1 agonists used in the acute treatment of migraine. They are generally used second line when standard analgesics such as paracetamol and ibuprofen are ineffective
Prescribing points Triptans:
- Should be taken as soon as possible after the onset of headache, rather than at onset of aura
- Oral, orodispersible, nasal spray and subcutaneous injections are available
Adverse effects - ‘Triptan sensations’ - tingling, heat, tightness (e.g. Throat and chest), heaviness, pressure
Contraindications - Patients with a history of, or significant risk factors for ischemic heart disease or cerebrovascular disease
Dopamine Receptor Agonists:
Indications
* Parkinson’s disease
* Prolactinoma/galactorrhoea
* Cyclical breast disease
* Acromegaly
Adverse effects
* Nausea/vomiting
* Postural hypotension
* Hallucinations
* Daytime somnolence
Benzodiazepines
enhance the effect of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). They therefore are used for a variety of purposes:
* Sedation
* Hypnotic
* Anxiolytic
* Anticonvulsant
* Muscle relaxant
The BNF gives advice on how to withdraw a benzodiazepine. The dose should be withdrawn in steps of about 1/8 (range 1/10 to 1/4) of the daily dose every fortnight. A suggested protocol for patients experiencing difficulty is given:
- Switch patients to the equivalent dose of diazepam
- Reduce dose of diazepam every 2-3 weeks in steps of 2 or 2.5 mg
- Time needed for withdrawal can vary from 1 month to 1 year or more
Amiodarone
class III antiarrhythmic agent used in the treatment of both atrial and ventricular tachycardias.
ain mechanism of action is by blocking potassium channels which inhibits repolarisation and hence prolongs the action potential. Amiodarone also has other actions such as blocking sodium channels (a class I-a effect)
The use of amiodarone is limited by a number of factors
- Long half-life (20-100 days)
- Should ideally be given into central veins (causes thrombophlebitis)
- Has proarrhythmic effects due to lengthening of the QT interval
- Interacts with drugs commonly used concurrently e.g. ↓ metabolism of warfarin = P450 inhibtor
- Numerous long-term adverse effects (see below)
Monitoring of patients taking amiodarone
TFT, LFT, U&E, CXR prior to treatment. U&E to check hypokalemia
* TFT, LFT every 6 months
Adverse effects of amiodarone use
- Thyroid dysfunction
- Corneal deposits
- Pulmonary fibrosis/pneumonitis
- Liver fibrosis/hepatitis
- Peripheral neuropathy, myopathy
- Photosensitivity
- ‘Slate-grey’ appearance
Amiodarone-induced hypothyroidism (AIH)
The pathophysiology of amiodarone-induced hypothyroidism (AIH) is thought to be due to the high iodine content of amiodarone causing a Wolff-Chaikoff effect (an autoregulatory phenomenon where thyroxine formation is inhibited due to high levels of circulating iodide)
Flecainide moa
Vaughan Williams class I-c antiarrhythmic. It slows conduction of the action potential by acting as a potent sodium channel blocker. This may be reflected by widening of the QRS complex and prolongation of the PR interval
Flecainide and MI
lecainide was actually shown to ↑ mortality post myocardial infarction and is therefore contraindicated in this situation.
Flecainide indications
Indications
* Atrial fibrillation
* SVT associated with accessory pathway e.g. Wolf-Parkinson-White syndrome
Adverse effects
* Negatively inotropic
* Bradycardia
* Proarrhythmic
* Oral paraesthesia
* Visual disturbance
Statins Moa
inhibit the action of HMG-CoA reductase, the rate-limiting enzyme in hepatic cholesterol
synthesis → Statins: ↓ cholesterol synthesis.
Statins Adverse effects
Myopathy: includes myalgia, myositis, rhabdomyolysis and asymptomatic raised creatine kinase. Risks factors for myopathy include advanced age, ♀, low BMI and presence of multisystem disease such as diabetes mellitus. Myopathy is more common in lipophilic statins (simvastatin, atorvastatin) than relatively hydrophilic statins (rosuvastatin, pravastatin, fluvastatin)
* Liver impairment: 2008 NICE guidelines recommend checking LFTs at baseline, 3 months and 12 months. Treatment should be discontinued if serum transaminase concentrations rise to and persist at 3 times the upper limit of the reference range
Statins (HMG CoA reductase inhibitors) AE
Myositis, pruritus, cholestasis
Nicotinic Acid
reatment of patients with hyperlipidemia, although its use is limited by side-effects. As well as lowering cholesterol and triglyceride concentrations it also raises HDL levels
Adverse effects
* Flushing
* Impaired glucose tolerance
Myositis
β-blocker overdose management
: atropine + glucagon
Glucagon has a positive inotropic action on the heart and ↓ renal vascular resistance. It is therefore
useful in patients with β-blocker cardiotoxicity
Hemodialysis is not effective in β-blocker overdose
β-Blocker Cardiotoxicity Features
Bradycardia
* Hypotension
* Heart failure
* Syncope
Furosemide moa
inhibiting chloride absorption in the ascending loop of Henle. The name of Lasix is derived from lasts six (hours) referring to its duration of action.
Furosemide AE
Adverse effects
* Hyponatremia
* Hypokalemia
* Hypocalcaemia
* Hypochloraemic alkalosis (Hyper pH)
* Ototoxicity
* Renal impairment (from dehydration + direct toxic effect)
* Hyperglycaemia (less common than thiazides)
* Gout
Bendroflumethiazide MOA
thiazide diuretic which works by inhibiting sodium absorption at the beginning of the distal convoluted tubule (DCT)
mechanism of Hypokalemia:
* ↑ sodium reaching the collecting ducts
* Activation of the renin-angiotensin-aldosterone
Bendroflumethiazide Common adverse effects
- Dehydration
- Postural hypotension
- Hyponatremia, Hypokalemia, Hypercalcemia
- Gout
- Impaired glucose tolerance, Hyperglycaemia
- Impotence
Spironolactone
aldosterone antagonist which acts act in the distal convoluted tubule
Spironolactone Adverse effects
- Hyperkalemia * Gynaecomastia
Adenosine:
Adenosine
* Dipyridamole enhances effect
* Aminophylline ↓ effect
Causes transient heart block in the AV node
* Agonist of the A1 receptor which inhibits adenylyl cyclase thus reducing cAMP and causing
hyperpolarization by increasing outward potassium flux
* Adenosine has a very short half-life of about 8-10 seconds
Adverse effects Adenosine:
Chest pain
* Bronchospasm
* Can enhance conduction down accessory pathways, resulting in ↑ ventricular rate (e.g. WPW)
Calcium channel blockers SE
side-effects: headache, flushing, ankle edema
Dihydropyridines (e.g. nifedipine, amlodipine)
Effects peripheral circulation i.e. Used for hypertension, raynaud’s
* May bring on angina due to sympathetic reflex following vasodilation
* Side-effects: headache, flushing, ankle edema
Verapamil, Diltiazem
- Contraindications: heart failure, heart block, on β-blockers
- Side-effects: headache, constipation, heart block
Aspirin MOA
works by blocking the action of both cyclooxygenase-1 and 2.
Hypotension, bradycardia, heart failure, ankle swelling
Ca Channel Blocker
Indications & Notes SE / CI
Verapamil
Angina, hypertension, arrhythmias Highly negatively inotropic
Should not be given with beta-blockers as may cause heart block
Heart constipation, hypotension, bradycardia
failure,
Diltiazem
Nifedipine, amlodipine, felodipine (dihydropyridines)
Hypertension, angina, Raynaud’s Flushing, headache, ankle swelling
Affects the peripheral vascular smooth muscle more than the myocardium and therefore do result in worsening of heart failure (but not amlodepine)
Cyclooxygenase is responsible for prostaglandin, prostacyclin and thromboxane synthesis. The blocking of thromboxane A2 formation in platelets reduces the ability of platelets to aggregate which has lead to the widespread use of low-dose aspirin in cardiovascular disease. All patients with established cardiovascular disease should take aspirin if there is no contraindication.
ho should receive aspirin according to the current guidelines
All people with established cardiovascular disease (stroke, TIA, IHD, peripheral arterial disease)
* All people aged 50 years and over with a 10-year cardiovascular risk = 20%
* All people with diabetes mellitus (type 1 or 2) who are = 50 years old or who have: diabetes >
10 years, taking treatment for hypertension or evidence of target organ damage
* All people with target organ damage from hypertension
Who should receive aspirin according to the current guidelines?
All people with established cardiovascular disease (stroke, TIA, IHD, peripheral arterial disease)
* All people aged 50 years and over with a 10-year cardiovascular risk = 20%
* All people with diabetes mellitus (type 1 or 2) who are = 50 years old or who have: diabetes >
10 years, taking treatment for hypertension or evidence of target organ damage
* All people with target organ damage from hypertension
Angiotensin-converting enzyme (ACE) inhibitors Moa
Mechanism of action:
* Inhibit the conversion angiotensin I to angiotensin II
ace SE
Side-effects:
* Cough: occurs in around 15% of patients and may occur up to a year after starting treatment. Thought to be due to increased bradykinin levels
* Angioedema: may occur up to a year after starting treatment
* Hyperkalaemia
st
* 1 -dose hypotension: more common in patients taking diuretics
Cautions and contraindications ACEi
Pregnancy and breastfeeding - avoid
* Renovascular disease - significant renal impairment may occur in patients who have
undiagnosed bilateral renal artery stenosis
* Aortic stenosis - may result in hypotension
* Patients receiving high-dose diuretic therapy (more than 80 mg of furosemide a day) -
signficantly increases the risk of hypotension
* Hereditary of idiopathic angioedema
ACEi Monitoring
Urea and electrolytes should be checked before treatment is initiated and after increasing dose
* A rise in the creatinine and potassium may be expected after starting ACE inhibitors. Acceptable increases are an increase in serum creatinine, up to 50% from baseline or up to 265
μmol/l (whichever is smaller) and an increase in potassium up to 5.5 mmol/l.
Acute Gout
Colchium alkaloids
*colchicine
NSAIDS
*indoethacine *Naproxen *Phenylbutazone *Ibuprofen
Chronic Gout
Uricosuric
*probenecid
*sulfinpyazone
Xanthine Oxidase Inhibitor
*allopurinol
Allopurinol
is used in the prevention of gout. It works by inhibiting xanthine oxidase which is responsible for the oxidation of 6-mercaptopurine to 6-thiouric acid
Initiating allopurinol prophylaxis - see indications
- Allopurinol should not be started until 2 weeks after an acute attack has settled
- Initial dose of 100 mg od, with the dose titrated every few weeks to aim for a serum uric acid of
< 300 μmol/l - NSAID or colchicine cover should be used when starting allopurinol
Indications for allopurinol
Recurrent attacks - the British Society for Rheumatology recommend ‘In uncomplicated gout
uric acid lowering drug therapy should be started if a second attack, or further attacks occur
within 1 year’
* Tophi
* Renal disease
* Uric acid renal stones
* Prophylaxis if on cytotoxics or diuretics
* Patients with Lesch-Nyhan syndrome often take allopurinol for life
Interactions
Azathioprine
- Metabolised to active compound 6-mercaptopurine
- Xanthine oxidase is responsible for the oxidation of 6-mercaptopurine to 6-thiouric acid
- Allopurinol can therefore lead to high levels of 6-mercaptopurine
- A much ↓ dose (e.g. 25%) must therefore be used if the combination cannot be avoided
Interactions
Cyclophosphamide
Allopurinol ↓ renal clearance, therefore may cause marrow toxicity
Hormone Replacement Therapy (HRT) indications
Indications
* Vasomotor symptoms such as flushing, insomnia and headaches
* Premature menopause: should be continued until the age of 50 years
* Osteoporosis: but should only be used as second-line treatment
Hormone Replacement Therapy (HRT) SE
Side-effects
* Nausea
* Breast tenderness
* Fluid retention and weight gain
HRT SE
Side-effects
* Nausea
* Breast tenderness
* Fluid retention and weight gain
HRT Potential complications HRT
↑ Risk of breast cancer: ↑ by the addition of a progestogen
* ↑ Risk of venous thromboembolism: ↑ by the addition of a progestogen
* ↓ Risk of endometrial cancer: ↓ by the addition of a progestogen but not eliminated completely.
The BNF states that the additional risk is eliminated if a progestogen is given continuously
Combined OCP: HRT
↑ Risk of breast cancer
↑ Risk of DVT
↓ Risk of endometrial ca.
Combined Oral Contraceptive Pill:Examples of UKMEC 3 conditions include
Examples of UKMEC 3 conditions include
* More than 35 years old and smoking less than 15 cigarettes/day
* BMI 35-39 kg/m2
* Migraine without aura and more than 35 years old
* Family history of thromboembolic disease in first degree relatives < 45 years
* Controlled hypertension
* Breast feeding 6 weeks - 6 months postpartum
Combined Oral Contraceptive Pill:
Examples of UKMEC 4 conditions include
- More than 35 years old and smoking more than 15 cigarettes/day
- BMI > 40 kg/ m2
- Migraine with aura
- History of thromboembolic disease or thombogenic mutation
- History of stroke or ischemic heart disease
- Uncontrolled hypertension
- Breast cancer
- Major surgery with prolonged immobilisation
Tamoxifen
is a selective estrogen receptor modulator (SERM) which acts as an estrogen receptor antagonist and partial agonist. It is used in the management of estrogen receptor positive breast cancer
Tamoxifen AE
Adverse effects
* Hot flushes
* Menstrual disturbance: vaginal bleeding, amenorrhoea
* V enous thromboembolism
* Endometrial cancer
* Alopecia
* Cataracts
Raloxifene
is a pure estrogen receptor antagonist, and carries a lower risk of endometrial cancer
Warfarin
is an oral anticoagulant which inhibits the reduction of vitamin K to its active hydroquinone form, which in turn acts as a cofactor in the formation of clotting factor II, VII, IX and X (mnemonic = 1972) and protein C
Dentistry in warfarinised patients
chheck INR 72 hours before procedure, proceed if INR < 4.0
Factors that may potentiate warfarin
- Liver disease
- P450 enzyme inhibitors, e.g.: amiodarone, ciprofloxacin
- Cranberry juice
- Drugs which displace warfarin from plasma albumin, e.g. NSAIDs
- Inhibit platelet function: NSAIDs
Side-effects warfarin
Hemorrhage
* Teratogenic
* Skin necrosis: when warfarin is first started biosynthesis of protein C is ↓. This results in a
temporary procoagulant state after initially starting warfarin, normally avoided by concurrent heparin administration. Thrombosis may occur in venules leading to skin necrosis
Warfarin overdose: Major bleeding
Stop warfarin
Vitamin K 5mg IV
Prothrombin complex concentrate - if not available then FFP*
Warfarin overdose:INR > 8.0
No bleeding or minor bleeding
Stop warfarin, restart when INR < 5.0
If risk factors for bleeding then give vitamin K 0.5mg IV or 5mg PO. Risk factors include:
* Age > 70 years
* First year of warfarin therapy
* History of gastrointestinal bleeding
* Hypertension
* Alcohol excess
Dose can be repeated after 24 hours if INR still high
INR 6.0 - 8.0
No bleeding or minor bleeding
Stop warfarin, restart when INR < 5.0
Acyclovir
Acyclovir is phosphorylated by thymidine kinase which in turn inhibits the viral DNA polymerase
Ribavirin
- Effective against a range of DNA and RNA viruses
- Interferes with the capping of viral mRNA
Interferons
Inhibit synthesis of mRNA, translation of viral proteins, viral assembly and release
Amantadine
- Used to treat influenza
- Inhibits uncoating of virus in cell
Nucleoside Analogue Reverse Transcriptase Inhibitors (NRTI)
Examples: zidovudine (AZT), didanosine, lamivudine, stavudine, zalcitabine
Protease inhibitors (PI)
Inhibits a protease needed to make virus able to survive outside the cell * Examples: indinavir, nelfinavir, ritonavir, saquinavir
Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTI)
(NNRTI)
examples: nevirapine, efavirenz
HIV: anti-retrovirals - P450 interaction
- nevirapine (NNRTI): induces P450
- protease inhibitors: inhibits P450
General NRTI side-effects:
peripheral neuropathy
* Zidovudine: anemia, myopathy, black nails
* Didanosine: pancreatitis
Protease inhibitors (PI) SE
Examples: indinavir, nelfinavir, ritonavir, saquinavir
* Side-effects: diabetes, hyperlipidemia, buffalo hump, central obesity, p450 enzyme inhibition
* Indinavir: renal stones, asymptomatic hyperbilirubinemia
* Ritonavir: a potent inhibitor of the p450 system
HIV: anti-retrovirals - P450 interaction
* nevirapine (NNRTI): induces P450
* protease inhibitors: inhibits P450
Cyclosporin moa
immunosuppressant which ↓ clonal proliferation of T cells by reducing IL-2 release. It acts by binding to cyclophilin forming a complex which inhibits calcineurin, a phosphotase that activates various transcription factors in T cells
Cyclosporin + tacrolimus
inhibit calcineurin thus decreasing IL-2
Adverse effects of Cyclosporin
- Nephrotoxicity
- Hepatotoxicity
- Fluid retention
- Tremor
- Hypertension
- Hyperkalemia
- Hypertrichosis
- Hyperplasia of gum
- Impaired glucose tolerance, hyperglycemia.
Tacrolimus
Tacrolimus is a macrolide antibiotic and is used as an immunosuppressant to prevent transplant rejection. It has a very similar action to Cyclosporin; the action of tacrolimus differs in that it binds to a protein called FKBP rather than cyclophilin
Tacrolimus is more potent than Cyclosporin and hence the incidence of organ rejection is less. However, nephrotoxicity and impaired glucose tolerance is more common
Azathioprine
metabolised to the active compound mercaptopurine, purine synthesis inhibitor, inhibiting the proliferation of cells, especially leukocytes/lymphocytes.
autoimmune diseases, or in combination with other immunosuppressants in organ transplantation. Caution should be exercised when it is used in conjunction with purine analogues such as allopurinol, you may give only 25% of the usual dose of azathioprine. Thiopurine methyltransferase (TPMT) deficiency is present in about 1 in 200 people and predisposes to azathioprine related pancytopaenia. A thiopurine methyltransferase (TPMT) test may be needed to look for individuals prone to azathioprine toxicity
Azathioprine SE
- Bone marrow depression
- Nausea/vomiting
- Pancreatitis
Methotrexate
antimetabolite which inhibits dihydrofolate reductase, an enzyme essential for the synthesis of purines and pyrimidines
Methotrexate - Adverse effects
Adverse effects
* Mucositis
* Myelosuppression * Pneumonitis
* Liver cirrhosis
Prescribing methotrexate
- Methotrexate is a drug with a high potential for patient harm. It is therefore important that you are familiar with guidelines relating to its use
- Methotrexate is taken weekly, rather than daily
- FBC, U&E and LFTs need to be regularly monitored. The Committee on Safety of Medicines
recommend ‘FBC and renal and LFTs before starting treatment and repeated weekly until
therapy stabilised, thereafter patients should be monitored every 2-3 months’ - Folic acid 5mg once weekly should be coprescribed, taken more than 24 hours after
methotrexate dose - The starting dose of methotrexate is 7.5 mg weekly
- Only one strength of methotrexate tablet should be prescribed (usually 2.5 mg)
- Avoid prescribing trimethoprim or cotrimoxazole concurrently - increases risk of marrow
aplasia
Mycophenolate mofetil
nhibits inosine monophosphate dehydrogenase
Methotrexate
antimetabolite which inhibits dihydrofolate reductase
Rituximab: se
Side effects:
* Flu-like illness
* ↓BP during fever
* Tumor side pain
Finasteride
an inhibitor of 5-α-reductase, an enzyme which metabolises testosterone into dihydrotestosterone. Its indications are:
* Benign prostatic hyperplasia
* ♂-pattern baldness
Finasteride se
Adverse effects:
* Impotence
* ↓ libid
* Ejaculation disorders
* Gynaecomastia and breast tenderness
Finasteride causes ↓ levels of serum prostate specific antigen
Bisphosphonates
analogues of pyrophosphate, a molecule which ↓ demineralisation in bone.
They inhibit osteoclasts by reducing recruitment and promoting apoptosis
Bisphosphonates SE
Adverse effects
* Esophageal reactions: oesophagitis, esophageal ulcers (especially alendronate)
* Osteonecrosis of the jaw
* MHRA has warned about an increased risk of atypical stress fractures of the proximal femoral
shaft in patients taking alendronate
Sildenafil
a phosphodiesterase type V inhibitor used in the treatment of impotence
Viagra - contraindicated by
nitrates and nicorandil
Nicorandil has a nitrate component as well as being a potassium channel activator The BNF recommends avoiding α-blockers for 4 hours after sildenafil
Sildenafil CI
Contraindications
* Patients taking nitrates and related drugs such as nicorandil
* Hypotension
* Recent stroke or myocardial infarction
* Non-arteritic anterior ischemic optic neuropathy
Adverse effects Sildenafil
- Visual disturbances e.g. Blue discoloration, non-arteritic anterior ischemic neuropathy
- Nasal congestion
- Flushing
- Gastrointestinal side-effects
Octreotide:
Overview
* Long-acting analogue of somatostatin
* Somatostatin is release from D cells of pancreas and inhibits the release of growth hormone
Uses
* Acute treatment of variceal hemorrhage
* Acromegaly
* Carcinoid syndrome
* Prevent complications following pancreatic surgery
* VIPomas
Octreotide:
Adverse effects
* Gallstones (secondary to biliary stasis)
Theophylline,
The main use of
theophyllines in clinical medicine is as a bronchodilator in the management of asthma and COPD
The exact mechanism of action has yet to be discovered. One theory suggests theophyllines may be a non-specific inhibitor of phosphodiesterase resulting in ↑ cAMP. Other proposed mechanisms include antagonism of adenosine and prostaglandin inhibition
Theophylline poisoning features:
Acidosis, Hypokalemia
* V omiting
* Tachycardia, arrhythmias
* Seizures
Theophylline poisoning Management
Activated charcoal
* Charcoal hemoperfusion is preferable to hemodialysis
Alcohol Withdrawal Mechanism
- Chronic alcohol consumption enhances GABA mediated inhibition in the CNS (similar to benzodiazepines) and inhibits NMDA-type glutamate receptors
- Alcohol withdrawal is thought to lead to the opposite (↓ inhibitory GABA and ↑ NMDA glutamate transmission)
Alcohol Withdrawal features
Features
* Symptoms start at 6-12 hours
* Peak incidence of seizures at 36 hours
* Peak incidence of delirium tremens is at 72 hours
Management
* Benzodiazepines
* Carbamazepine also effective in treatment of alcohol withdrawal
* Phenytoin is said not to be as effective in the treatment of alcohol withdrawal seizures
Proton Pump Inhibitors (PPI)
group of drugs which profoundly ↓ acid secretion in
the stomach. They irreversibly block the hydrogen/potassium adenosine triphosphatase enzyme system
(the H+/K+ ATPase) of the gastric parietal cell. Examples include omeprazole and lansoprazole.
Aminosalicylates:
5-aminosalicyclic acid (5-ASA) is released in the colon and is not absorbed. It acts locally as an anti-inflammatory. The mechanism of action is not fully understood but 5-ASA may inhibit prostaglandin synthesis
Sulphasalazine
A combination of sulphapyridine (a sulphonamide) and 5-ASA
* Many side-effects are due to the sulphapyridine moiety: rashes, oligospermia, headache, Heinz
body anemia
* Other side-effects are common to 5-ASA drugs (see mesalazine)
Mesalazine
- A delayed release form of 5-ASA
- Sulphapyridine side-effects seen in patients taking sulphasalazine are avoided
- Mesalazine is still however associated with side-effects such as GI upset, diarrhea, headache,
agranulocytosis, pancreatitis*, interstitial nephritis
Immunoglobulins: Therapeutics
The Department of Health issued guidelines on the use of intravenous immunoglobulins in May 2008
Uses
- Primary and secondary immunodeficiency
- Idiopathic thrombocytopenic purpura (ITP)
- Myasthenia gravis
- Guillain-Barre syndrome
- Kawasaki disease
- Toxic epidermal necrolysis (TEN)
- Pneumonitis induced by CMV following transplantation
- Low serum IgG levels following hematopoietic stem cell transplant for malignancy
- Dermatomyositis
- Chronic inflammatory demyelinating polyradiculopathy
Inhibit cell wall formation
*Penicillins
* Cephalosporins * Isoniazid
* V ancomycin
Inhibit protein synthesis
*aminoglycosides (cause misreading of mRNA)
* chloramphenicol *macrolides (e.g.
erythromycin)
* tetracyclines *fusidic acid
* (Quin/Dalfo)pristin * Linezolid
Inhibit DNA synthesis
*quinolones (e.g. ciprofloxacin)
* metronidazole
* sulphonamides * trimethoprim
inhibit RNA synthesis
rifampicin
Bactericidal antibiotics
- Penicillins
- Cephalosporins
- Isoniazid
- Aminoglycosides
- Quinupristin+Dalfopristin (combination)
- Metronidazole
- Quinolones: ciprofloxacin, levofluxacin
- Rifampicin
- Nitrofurantoin → Damages bacterial DNA
Bacteriostatic antibiotics
- Chloramphenicol
- Macrolides
- Tetracyclines
- Fusidic acid
- Quinupristin
- Dalfopristin
- Linezolid
- Sulphonamides
- Trimethoprim
Erythromycin
1st macrolide used clinically. Newer examples include clarithromycin and azithromycin. Erythromycin may potentially interact with amiodarone, warfarin and simvastatin
Macrolides act by inhibiting bacterial protein synthesis. If pushed to give an answer they are bacteriostatic in nature, but in reality this depends on the dose and type of organism being treated.
Erythromycin is used in gastroparesis as i
it has prokinetic properties, Promotes gastric emptying
Adverse effects of erythromycin
- GI side-effects are common
- Cholestatic jaundice: risk may be ↓ if erythromycin stearate is used
- P450 inhibitor
Quinolone’s
group of antibiotics which work by inhibiting DNA synthesis and are bactericidal in nature. Examples include:
* Ciprofloxacin * Levofloxacin
Adverse effects Quinolone’s
- Lower seizure threshold in patients with epilepsy
- Tendon damage (including rupture) - the risk is ↑ in patients also taking steroids. Achilles
tendon ruptures. Tendon damage is a well documented complication of quinolone therapy. It appears to be an idiosyncratic reaction, with the actual median duration of treatment being 8 days before problems occur
Quinupristin & Dalfopristin Antibiotics
Overview
* Injectable streptogrammin antibiotic
* Combination of group A and group B streptogrammin
* Inhibits bacterial protein synthesis by blocking tRNA complexes binding to the ribosome
Spectrum
* Most Gram positive bacteria
* Exception: Enterococcus faecalis
Quinupristin & Dalfopristin Antibiotics AE
Adverse effects
* Thrombophlebitis (give via a central line)
* Arthralgia
* P450 inhibitor
Linezolid
type of oxazolidonone antibiotic which has been introduced in recent years. It inhibits bacterial protein synthesis by stopping formation of the 70s initiation complex and is bacteriostatic nature
Linezolid adverse effects
Adverse effects
* Thrombocytopenia (reversible on stopping)
* Monoamine oxidase inhibitor: avoid tyramine containing foods
Sulfonamides
Antibacterial sulfonamides act as competitive inhibitors of the enzyme dihydropteroate synthetase (DHPS), an enzyme involved in folate synthesis.
Co-trimoxazole:
: sulfonamide antibiotic combination of trimethoprim and sulfamethoxazole, in the ratio of 1 to 5, used in the treatment of a variety of bacterial infections.
Diethylcarbamazine: