Pharmacology Flashcards
Patients on long term steroid therapy, due to to operation.
What to do with steroids?
If already receiving therapeutic dose (e.g. for COPD, asthma, rheumatoid arthritis)
—> Continue with the usual daily dose
If on physiologic replacement doses (e.g. for Addison’s disease)
—> Should receive additional 50mg of hydrocortisone intraoperatively
Contraindications to use nitrates
- SBP < 90mmHg
- HR < 50bpm or > 100 bpm
- Known right ventricular infarction
- Severe aortic stenosis
- Hypertrophic cardiomyopathy
Can lead to cardiac decompensation and haemodynamic instability
Sulphonylureas
Mechanism of action
- most wifely used drugs for T2DM
- gliclazide, glimepiride, glipizide
- stimulates pancreatic beta cells and causes secretion of insulin
- may also have extrapancreatic effects — increases tissue sensitivity to insulin (minimal effects though)
Best initial treatment of Parkinson’s disease
What to do when overstimulated?
Carbidopa/levodopa
- may develop dyskinesia after a few months
- due to overstimulation of dopamine receptors
- so must reduce the dose without loss of therapeutic efficacy
- alternative/can be added if cannot achieve: amantadine, pergolide
What antiepileptic drugs induces liver enzymes?
Side effects of these drugs on pregnant women?
What do to with women who are on antiepileptics and require OCPs?
Carbamazepine, phenytoin, barbiturates (phenobarbital), topiramates
High risk of teratogenicity: cleft lip or palate, cardiac anomalies, neural tube defects and hypospadias
RACGP: OCP with high estrogen content (Microgynon 50) should be used to minimise the risk of “pill failure”
If possible, ++ barrier method with condom.
[Not even progesterone-only pills should be used]
Gentamicin ~ botulism
Gentamicin
- prevents the release of acetylcholine from nerve endings like botulinum toxin
- can cause muscle paralysis in high risk patients
- if eliminate drug, symptoms subsides rapidly
- best avoided in those with pre-existing disturbance to neuromuscular transmission (myasthenia gravis)
Treatment for essential tremor
Propranolol or primidone
However, propranolol should be avoided in those contraindicated to BB (such as severe asthma)
If above fails benzodiazepines can be considered in low doses.
Under what circumstances can a patient continue to take hypnotics (such as temazepam or zolpidem etc) for more than 6 months or even years?
- Patient must be aware that they are dependent on that specific hypnotics
- No history of any adverse event/side effects from said medication
- Reduction program has been unsuccessful
If plan to stop, stop it gradually, not abruptly.
ECG of Digitalis Toxicity
- ST depression and T wave inversion in V5-V6 in reversed tick pattern
- Bradycardia
- Prolonged PR
- Shortened QT
- Arrhythmias, especially heart block or bigeminy
POP is not a reliable contraception in women taking enzyme-inducing antiepileptic drugs
There is one exception - which drug is it?
Sodium Valproate
Most prominent ECG abnormalities in tricyclic antidepressant (amitriptyline) overdose
- WIDENED QRS INTERVAL
Others:
- Prolonged PR and QT intervals
- VT/VF (4% of cases)
- Sinus tachycardia (anticholinergic effect and reflex tachycardia due to haemodynamic decompensation)
Most common cause of false positive elevation of plasma normetanephrine and norepinephrine level in those suspected to have phaeochromocytoma?
Tricyclic Antidepressants and Phenoxybenzamine
- 45% of the cases
- Fasting urinary metanephrines should be checked after stopping counfounding drugs
Other causes:
- Congestive cardiac failure
- Major depression
- Panic disorder
INR 5-9, no evidence of significant bleeding, what to do with warfarin?
Stop warfarin, give oral or IM vitamin K and check INR in 24H
If significant bleeding occurs before next blood taking, give urgent prothrombinex VF or FFP
INR 5-9
What constitutes clinically significant bleeding requiring immediate reversal of INR?
- intracranial bleeding
- retroperitoneum bleeding
- intraocular bleeding
- muscle bleed with compartment syndrome
- pericardial bleed
- active bleed with hypotension or 2g fall in haemoglobin
What PSY drugs are likely to cause alopecia or hair loss?
Lithium
Valproate
Carbamazepine
Phenytoin
How long it takes to see therapeutic effects of IV Vitamin K1 (Phytomenadione)?
6-8 Hours
Oral takes longer.
Combination of gabapentin and amoxicillin can cause…
Hepatotoxicity
Earliest sign of dose-related toxicity of carbamazepine
Diplopia, observed within 60 minutes after the morning dose
Donepezil
Contraindications
Donepezil
- anticholinesterase drug (decrease breakdown of acetylcholine)
- reduces apparent deficiency of cholinergic neurotransmitter activity in Alzheimer’s disease
- improves alertness and function, maintains cognitive scores for up to 12 months
- must do ECG TRO heart block of bradycardia before starting
Contraindications
- GI or ureteric obstruction
- active peptic ulcer
- heart block
- Bradyarrhythmias (including sick sinus syndrome)
- COPD
- Parkinson’s disease
Raloxifene
- Selective oestrogen receptor modulator (SERM)
- prevents postmenopausal bone loss
- reduces risk of vertebral fractures (not non-vertebral)
- reduces risk of breast CA
- hot flushes
- increases risk of DVT
Maximum dose is 60mg
If failed, do not combine with another osteoporosis treatment (not recommended)
What group of antibiotics increases risk of ligament rupture?
Fluoroquinolone (e.g. Ciprofloxacin)
[Case: Male over 40 years old, on ciprofloxacin, acute pain and loss of function of posterior aspect of the lower leg, rupture of Achilles tendon]
Proton Pump Inhibitor (such as Omeprazole)
Mechanism of action
- profoundly reduces acid secretion in the stomach by up to 99%
- irreversibly blocks the hydrogen-potassium ATPase enzyme system in the gastric parietal cells
[Case: Cimetadine (antihistamine on H2 receptor), on the other hand, has reversible blockage]
Contraindications to Warfarin
- Active bleeding
- Uncontrolled hypertension
- History of intracranial bleeding
- Liver disease with impaired synthetic functions
- Pregnancy
Acute side effects with a course of prednisolone
(Short list)
Hyperglycaemia
Hypertension
Fluid retention
Myopathy
Psychological disturbances
Drugs that can antagonise cholinesterase inhibitors (Donepezil, galantine and rivastigmine)
Drugs with anticholinergic activity (amitriptyline, promethazine, oxybutynin)
Anticholinergic Drugs VS Acetylcholinesterase Inhibitors (ACHEIs)
Anticholinergic Drugs
- block the transmission of acetylcholine in the central and peripheral nervous system
Acetylcholinesterase Inhibitors (ACHEIs)
- increase availability of acetylcholine by blocking the enzyme (acetylcholinesterase) that breaks it down
Adenosine
- Treatment of choice for paroxysmal SVT
- blocks transmission through AV nodes
- Short half life: 10-15 SECONDS
- Contraindicated in patients with asthma, WPW etc
Antidote for heparin
Protamine sulphate
If active bleeding, use FFP
What common analgesic causes premature closure of the fetal ductus arteriosus?
NSAIDS is safe to use up to 32 weeks.
After 32 weeks, risk:
- premature closure of the fetal ductus arteriosus
- delay labour and birth
- oligohydramnios via an effect on fetal renal function
Osteonecrosis of the jaw
IV BISPHOSPHONATES (alendronate, zoledronic acid, risedronate)
(Rarely seen with oral route bisphosphonates)
Side Effects of Tricyclic Antidepressants
Anticholinergic and Non-Cholinergic side effects:
- Dry mouth
- Sedation
- Confusion
- Delirium
- Urinary retention
- Glaucoma
- Tremors
- Weight gain
- Postural hypotension
- Sexual dysfunction
- Lowered seizure threshold
Anticholinergic Toxidrome:
Mad as a Hatter
Blind as a Bat
Dry as a Bone
Red as a Beat
Hot as a Dessert
- absent bowel sounds, tachycardia, shaking, grabbing invisible objects, shaking, dilated pupils (mydriasis)
Anticholinergic Toxidrome
Mad as a Hatter
Blind as a Bat
Dry as a Bone
Red as a Beat
Hot as a Dessert
- absent bowel sounds, tachycardia, shaking, grabbing invisible objects, shaking, dilated pupils (mydriasis)
Theophylline
- oral bronchodilator
- for asthma and COPD
- well absorbed
What increases clearance from liver? (Good thing?)
- Ethanol
- Smoking
- High protein
- BBQ meat
- low carbohydrate diet
(So you would want to avoid high carb diet)
What does fibrates (such as gemfribrozil) do to warfarin?
+ increase warfarin’s anticoagulation effect
+ increase risk of bleeding
So must monitor INR and decrease warfarin dose
Bosentan (Tracleer)
Mechanism of action
Dual endothelin-receptor antagonist
- for treatment of pulmonary artery hypertension
- Competes against ET-A and ET-B which causes pulmonary vasoconstriction.
- By blocking interaction, decreases pulmonary vascular resistance
- higher affinity than ET-A and ET-B
Flucloxacillin
Side effects especially in older patients
Severe hepatitis and cholestatic jaundice
- especially in older patients and on prolonged periods
- on long term prescription —> must do weekly blood test to monitor LFT
Cefepime
- 4th generation cephalosporin
Used for?
Caveat?
Used to treat neutropenic fever, healthcare-associated fever and severe CAP
- particularly Pseudomonas aeruginosa
Caveat:
- neurotoxicity especially in older patient with compromised renal function
- delirium, encephalopathy, myoclonus
- EEG: nonconvulsive status epilepticus
Contraindications to progesterone-only contraceptive pills
- Severe active liver disease
- malabsorption syndromes
- undiagnosed vaginal bleeding
- previous ectopic pregnancy
- previous sex steroid-dependent cancers
How many days before sugery should a patient with high risk of thromboembolism alreayd on warfarin stop his warfarin?
If INR is > 5-9?
Traditionally, 5 days.
Check INR the next day + daily.
Anytime < 2, can start bridging with heparin.
INR has to be < 1.5 to proceed with surgery.
If the day before still > 1.5, can give IV Vit K1 3mg, and repear INR the next day.
However, any time it is > 5-9, without any evidence of bleeding, cease heparin/warfarin, give IV Vit K1 and repear INR the next day.
Prothrombinex-VF vs FFP
Which one is preferred for emergencies or ongoing bleeding?
If both options are available, Prothrombinex-VF is more desirable, as FFP is more “troublesome”.
Both must be given with IV Vit K1 dose.
What are the clinical benefits of beta blockers to the patient with heart failure when used in combination with ACE-I?
- Prevent hospitalisation
- Prolong life
- Reverse the process of LV remodelling
- Block he sustained activation of beta adrenergic receptors (alpha-1, beta-1, beta-2)
- Improve the patient symptoms
Tetracycline: Minocycline, Doxycycline, Tetracycline — are oral antibiotics used to treat Acne Vulgaris
What are the long term side effects of long-term minocycline therapy?
- Dental staining
- Severe photosensitivity
- Discolouration of the skin
- Pneumonitis
- Serum sickness
- Autoimmune hepatitis
Bisphosphonates
- Slows down bone loss, improve BMD, reduce fracture rates
- First line treatment of both osteoporosis and prevention of osteoporosis in postmenopausal women
- Should be continued for at least 5-7 years, with a review of BMD response every 1-2 years
Which drugs can cause pinpoint pupils?
[Common in those post surgery (opioids and barbiturates)]
- Structural pons disease
- Opiates (heroin and morphine)
- Barbiturates
- Organophosphates
- Clonidine
- Pilocarpine eye drops (parasympathomimetic alkaloid)
Haloperidol
Pinpoint pupils or mydriasis?
Antipsychotics medication — Mydriasis
Xanthine Oxidase Inhibitors are first line urate-lowering drugs. (Allopurinol)
- They decrease uric acid level and prevent gout attacks
What are their indications and contraindications?
Absolute indications
- Damage due to chronic gout seen on imaging
- Tophi development
- Frequent gout attacks (≥ 2 per year)
- Serum uric acid > 9 mg/dL on first presentation
- History of urolithiasis (urate kidney stones due to hyperuricaemia)
Contraindications
- Acute gout flare
- Advanced renal impairment — possible but require dosage adjustment — Must maintain U/O 2L/day + avoid the formation of xanthine calculi
Vitamin K antagonist = Warfarin
- used in the treatment of Anti-Phospholipid Syndrome (APS)
- used for the prevented of VTE
- depresses factor 7, 9, 10 and prothrombin in the blood
- INR reflects the warfarin dose given 48 hours earlier
- Thrombosis in APS is one of the indications to use warfarin
- contraindicated in pregnancy
[Case with underlying issues + acute gout]
Verapamil and NSAIDS
ACE-I and NSAIDS
Diuretic (Frusemide) and Gout
Verapamil and NSAIDS
Increases risk of bradycardia and pro-arrhythmic effect
ACE-I and NSAIDS
May cause renal dysfunction
Diuretic (Frusemide) and Gout
Decreases urate excretion —> diuretic-induced hyperuricaemia
Known adverse drug reaction for ACE-I
Angioedema (bradykinin-induced angioedema)
- may present with mild episodes and progress to having severe life-threatening episodes
- self-limiting
- could occur in isolation/with urticaria/a component of anaphylaxis
- gravity-independent areas: face, lips, tongue, uvula, larynx, extremities and genitalia, bowel wall (jejunum) (— colicky pain, obstruction, ascites)
Hereditary Angioedema (HAA)
VS
Acquired C1 Esterase Inhibitor (C1-INH) Deficiency
HAA - often in young patients
C1-INH Deficiency
- AKA Acquired Angioedema (AAE)
- Recurrent episodes of angioedema without urticaria
- often older than 40 years old
