Drugs Flashcards
What do you give for secondary prevention of MI?
Aspirin Clopidogrel Beta blocker ACEi Statin
4 anticipatory medications given by syringe driver at end of life
Pain- diamorphine
Agitation- midazolam
N+V- haloperidol
Secretions- hyoscine butylbromide
Side effect of omeprazole?
Hypomagnesaemia–> tetany and ventricular arrythmia
What is loperamide?
Anti-diarrhoeal
What is the generic name for loperamide?
Codeine phosphate
Does loperamide have analgesic effects?
No
How do opioids prevent diarrhoea/cause constipation?
Agonists of opioid u-receptors in GI tract, increases non-propulsive contractions and decreases propulsive (peristaltic) contractions. Transit is slowed and anal sphincter tone is increased. More time for water absorption so stool hardens.
Contraindications of loperamide?
Acute UC, C.diff and dysentry- as risk of megacolon and perforation.
Other name for senna?
Docusate
How does senna work?
Stimulant. Increase water and electrolyte secretion from colonic mucosa so colonic volume is increased and peristalsis increases. Also direct pro-peristaltic action
Contraindications of senna
Bowel obstruction
Avoid rectal route in haemorrhoids/anal fissure
What drug class is mesalazine/sulfasalazine?
Aminosalicylate
What is the indication for mesalazine?
Ulcerative colitis
What is the indication for sulfasalazine?
Rheumatoid arthritis
How does mesalazine work?
Topically on the gut. Releases 5-aminosalicylic acid- anti-inflammatory and immunosuppresant.
Why isn’t sulfasalazine used in UC?
broken down to sulfapyridine which treats RA but has side effects in UC.
Side effects of aminosalicylates
Leucopenia, thrombocytopenia, renal impairment, oligospermia
What is the route of mesalazine?
Rectal
What does metoclopramide do?
Anti-emitic
What class of drug are metoclopramide and domperidone?
Dopamine D2-receptor antagonists
How does metoclopramide/domperidone work?
D2 is the main receptor in the chemoreceptor trigger zone (area responsible for sensing emetogenic substances in the blood.) Dopamine is the neurotransmitter.
Also a neurotransmitter in the gut so increased gut motility (decreased gut motility may cause nausea)
Contraindications of metoclopramide/domperidone?
GI obstruction
Perforation
Side effect of metoclopramide/domperidone?
Extrapyramidal syndromes- acute dystonic reaction e.g. oculogyric crisis
Possible interactions of metoclopramide/domperidone?
Antipsychotics (increased risk of side effects)
Dopaminergic agents used in parkinsons (antagonises these)
What type of diuretic is furosemide?
Loop
How does furosemide work?
Inhibits Na/K/Cl co-transporters in the ascending loop of Henle so water doesn’t follow these ions into the cell. i.e. prevents water reabsorption.
Also vasodilation so reduces preload of heart and increased contractility of overstretched heart muscle.
Indications for furosemide?
Pulmonary oedema
Fluid overload e.g. CHF, liver failure, renal disease
Contraindications of furosemide
Hypovolaemia
Dehydration
Unexpected side effect of furosemide?
Hearing loss and tinnitus
Possible interactions of furosemide?
May effect drugs excreted by the kidneys e.g. increased risk of digoxin toxicity, of oto+nephrotoxicity of aminoglycosides
Name 2 thiazide like diuretics
Bendroflumethiazide
Indapamide
Where do thiazide like diuretics act
DCT
Contraindication of thiazide like diuretic
Hypokalaemia
Unexpected side effect of thiazide like diuretic
Impotence
Efficacy of thiazide like diuretics is reduced by what?
NSAIDs
Name 3 potassium sparing diuretucs
Amiloride
Co-amilofruse
Spironolactone
Where do potassium sparing diuretics act?
DCT
Indication for potassium sparing diuretic
Hypokalaemia from loop or thiazide diuretics- is used in combination as quite a weak diuretic alone.
Contraindications of potassium sparing diuretic
Renal impairment
Hyperkalaemia
Don’t start in hypokalaemia is unpredictable effects on K+
Name 2 alpha blockers
Doxazosin
Tamulosin
How do alpha blockers work
Block alpha 1 adrenoreceptors in smooth muscle (blood vessels, urinary tract) and cause vasodilation (lowers BP) and reduced resistance to bladder outflow
Indications for alpha blockers
BPH
Resistant HTN
Contraindications for alpha blockers
Postural hypotension
What should you do in terms of interactions on the first day of alpha blocker administration?
Stop beta blockers as block reflex tachycardia in response to vasodilation which could = syncope
When should alpha blockers be taken?
Bed time
Name a xanthine oxidase inhibitor
Allopurinol
How does allopurinol work?
Prevents the conversion of purine to xanthine (via inhibition of the enzyme xanthine oxidase), xanthine would normally go on to become uric acid. So plasma uric acid conc is lowered.
Indications for allopurinol
Prevents:
- gout
- uric acid/calcium oxalate renal stones
- hyperuricaemia
- tumour lysis syndrome
Contraindication of allopurinol
Acute gout attack (but continue if already take it)
Side effects of allopurinol
Skin rash (can=SJS/TEN) Trigger or worsen gout when start
Interactions of allopurinol
Inhibit mercaptopurine and azathioprine as they require xanthine oxidase for metabolism
Increased risk of rash to amoxicillin
Increased risk of hypersensitivity reactions to ACEi and thiazides.
Name 2 tricyclic antidepressants
Amitryptiline
Lofepramine
How do tricyclic antidepressants work?
Inhibit the reuptake of serotonin and noradrenaline
also block many receptors: muscarinic, histamine, alpha adrenergic and dopamine which lead to adverse effects!
Indications for tricyclic antidepressants
2nd line for depression
Neuropathic pain off licence
Side effects of tricyclic antidepressants
Dry mouth Constipation Urinary retention Blurred vision Sedation Hypotension Arrythmias/ECG changes Convulsions Hallucinations Mania Breast changes Sexual dysfunction Tremor/dyskinesia
Interactions of tricyclic antidepressants
Monoamine oxidase inhibitors (have same action so lead to HTN, hyperthermia, serotonin syndrome)
How long should antidepressants be taken for after remission?
6 months after start to feel better
Which platelet receptors does clopidogrel bind to? What does this do?
ADP receptors, prevents aggregation
Aspirin and clopidogrel act on the same/different pathway
Different
Indications for clopidogrel
ACS
Prevent stent occlusion
Long term secondary prevention of thrombotic arterial events
AF where warfarin or NOVACs c/i
Contraindications of clopidogrel
Bleeding
Stop 7 days before elective surgery
Side effects of clopidogrel
Bleeding
GI upset
Thrombocytopenia
Aspirin mechanism of action
COX inhibition (stops arachidonic acid turning into throboxane which is pro-aggregatory)
Is aspirin COX inhibition reversible?
No, lasts for lifetime of platelet
Indications of aspirin
ACS Ischaemic stroke Long term prevention of thrombotic events AF where warfarin/novac c/i Pain and fecer
Aspirin c/is
<16yo Reye’s syndrome risk
3rd trimester of pregnancy (ductus arteriosus)
Is propanolol a particularly selective or non selective beta blocker?
Non selective for B1
Which beta blocker has a particularly short half life?
Metoprolol
How do beta blockers work?
Act on B1 receptors in the heart, reduce force and speed of contraction. Less cardiac work and oxygen demand, increased myocardial perfusion.
Prolong the refractory period of the AV node
Reduce renin secretion from kidneys (mediated by b1 receptors)
Indications for beta blockers
Ischaemic heart disease CHF AF SVT HTN
Contraindications for beta blockers
Asthma
Heart block
Haemodynamic instability
Side effects of beta blockers
Fatigue Cold extremities Headache GI upset Sleep disturbance and nightmares Impotence
Interactions of beta blockers
Non dihydropyridine calcium channel blockers e.g. verapamil, dilitiazem as the combination can cause HF, bradycardia and even asystole
What are the two types of calcium channel blocker and what are they each selective for?
Non-dihydropyridines (heart)
Dihydropyridines (vasculature)
Dilitiazem is MIXED
Name 3 calcium channel blockers
Dilitiazem
Amlodipine
Verapamil
How do calcium channel blockers work
Decrease entry of calcium into vascular and cardiac cells so intracellular calcium conc is decreased. This = relaxation and vasodilation of arterial smooth muscle and decreases arterial pressure.
In heart reduces contractility and suppresses cardiac electrical conduction (esp AVN) so ventricular rate decreased so reduced O2 demand of heart.
Indications for Ca Ch bs
HTN
Stable angina
SVT
Contraindications of non-dihyd ca ch bs
AV node conduction delay
Caution if poor LV function
C/is of dihyd ca ch bs
unstable angina
severe aortic stenosis
Side effects of ca ch bs
Dihydro- Ankle swelling, flushing, headache, palpitations
Verapamil- constipation, bradycardia, heart block, CF
Possible interactions of calcium channel bl
Non dihydro with beta blockers. As both negatively inotropic and chronotropic
Name an ACEi
Ramipril
What does angiotensin II do?
Vasoconstriction and stimulates aldosterone
Contraindications of ACEi
Renal artery stenosis
AKI and caution in CKD
Pregnant
Side effects ACEi
Hypotension
Dry cough (increased bradykinin)
Hyperkalaemia
What type of drug is losartan
Angiotensin II type 1 receptor antagonist
How does losartan work
- Competes with angiotensin II to bind to the type 1 receptor.
- Decreased PVR
- Decreased aldosterone secretion means increased sodium and water excretion which reduces venous return
- Dilates efferent glom. arteriole so decreased intraglom pressure and slows progress of CKD
Indication for losartan
Generally when ACE not tolerated due to cough
- HTN
- CHF
- Ischaemic HD
- Diabetic nephropathy and CKD with proteinuria
Contraindications for losartan
Same as ACEi.
Renal artery stenosis, AKI and caution in CKD, pregnant
Possible interactions of losartan and ACEi
Other potassium elevating drugs
L dopa is always given with ?
Peripheral decarboxylase inhibitor
Name an L dopa (and PDI)
Sinemet, madopar
Side effects of L dopa
nausea drowsiness confusion hallucinations hypotension Wearing off effect and on-off effect
Possible interactions of L dopa/PDI
Antipschotics
Metoclopramide
What is phenytoin?
Anti-convulsant
How does phenytoin work?
Binds to inactive neuronal Na channels, prolonging the period of inactivity, so neuronal excitability decreased
Indication of phenytoin
- Stop status epilepticus of benzos not working
- Decrease frequency of epileptic seizures
What could phenytoin cause if taken in pregnancy?
Foetal hydantoin syndrome
Side effects of phenytoin
Skin coarsening Acne Hirsutism Gum hypertrophy Cerebellar toxicity Haem disorders Osteomalacia
Which drugs decrease the efficacy of phenytoin (not to do with P450)
Drugs that lower the seizure threshold e.g. SSRIs, tricyclics, antipsychotics, tramadol
What must patients taking phenytoin be cautious with?
Contraception
Which anticonvulsant can be used for trigeminal neuralgia
Carbamezapine
Which anticonvulsant is the worst teratogen
Sodium valproate
Which anticonvulsant interacts with oestrogen containing contraceptives
Lamotrigine
Which anticonvulsant can have psychiatric side effects including suicidal thoughts
Levetiracetam
How do cardiac nitrates work?
Decrease intracellular calcium so relaxation of smooth muscle
Interaction of nitrates
Slidenafil
Contraindications of nitrates
Severe aortic stenosis
Haemodynamic instability
Hypotension
Side effect of digoxin given its narrow therapeutic index
Digoxin toxicity
Digoxin contraindications
Heart block (2nd and 3rd degree) and ventricular arrhythmias
Digoxin interactions
Risk of digoxin toxicity increased by- diuretics, amiodarone, calcium channel blockers and quinine
Amiodarone indication
Treatment of tachyarrhythmias (life support)
Amiodarone contraindications
Hypotension, heart block, thyroid disease
How do heparins work
Inhibit thrombin and factor Xa
What type of anticoagulant is enoxaparin?
Heparin
How do statins work
Inhibit HMGCoA reductase (enzyme involved in making cholesterol)
What type of drug is tiotropium?
Antimuscarinic/anticholinergic
When are antimuscarinics contraindicated?
Angle closure glaucoma
What are acetylcholinesterase inhibitors used for?
Myasthenia gravis
Glaucoma
Alzheimers/dementia/parkinsons
What do antimuscarinics do?
Inhibit acetylcholine
How do 5-alpha reductase inhibs work?
inhibiting the intracellular enzyme 5α-reductase, which converts testosterone to its more active metabolite dihydrotestosterone. As dihydrotestosterone stimulates prostatic growth, inhibition of its production by 5α-reductase inhibitors reduces prostatic enlargement and improves urinary flow.
How long do 5-alpha reductase inhibs take to work?
Months
Side effects of 5-ARI
Impotence, reduced libido
Gynaecomastia
Hair growth
Breast cancer
Men taking 5-ARI must be careful not to……?
Have unprotected sex with a pregnant woman
How does gliclazide work
stimulates pancreatic insulin secretion
Side effect of gliclazide
Weight gain
Name a biguanide
Metformin
How does metformin work
increases the response (sensitivity) to insulin. It suppresses hepatic glucose production (glycogenolysis and gluconeogenesis), increases glucose uptake and utilisation by skeletal muscle and suppresses intestinal glucose absorption
Do metformin and gliclazide carry a risk of hypoglycaemia?
Metformin no, gliclazide yes
Contraindication of metformin
Severe renal impairment
