Cardiovascular Drugs
Diuretics
Thiazides
Mechanism:
Na/Cl co-transporter inhibitor in the distal convoluted tubules
Uses:
-
Relieve oedema in heart failure, e.g. Bendroflumethiazide 5-10mg daily in morning
-
Hypertension e.g. Bendroflumethiazide 2.5mg daily in morning.
Adverse effects:
Postural hypotension, ↓K, ↑Ca, ↓Mg, ↑Urate (→gout), impotence
Contraindications:
↓K, ↓Na, ↑Ca, hyperuricaemia, Addisons
Loop Diuretics
Mechanism:
Na/2Cl/K co-transporter inhibitor (ascending loop)
Uses:
-
Pulmonary oedema: IV Furosemide 80-250mg over 1 hour
-
Chronic stable heart failure: Oral furosemide 40mg in morning
-
Oliguria due to renal failure: evidence is tending away from this use nowadays. Correct hypovolaemia first.
-
Refractory hypertension
Adverse Effects:
Dehydration, ↓Na, ↓K, ↓Ca, ototoxic, urinary retention if enlarged prostate
Contraidications:
Renal failure with anuria, pre-comatose states associated with liver cirrhosis
Potassium Sparing
Mechanism:
Inhibit sodium reabsorption in the distal convoluted tubules and collecting ducts
Uses:
Oedema, Heart failure, potassium conservation with thiazide/loop diuretics
Dose:
5mg daily
Adverse Effects:
GI upset, ↑K
Contraindications:
Hyperkalaemia, renal failure
ACE Inhibitors
Mechanism:
Inhibit the conversion of angiotensin I to angiotensin II
Uses:
Heart failure, hypertension, diabetic nephropathy, prophylaxis of CVS events]
Dose:
Hypertension/heart failure - Captopril 25mg bd
Adverse Effects: Cough, hypotension, renal impairment, anaphylaxis, rash, pancreatitis, URT sx, GI sx
Contraindications:
Hypersensitivity, renovascular disease
Beta Blockers
Mechanism:
Block beta receptors in heart, vasculature, bronchi, pancreas, liver
Uses:
Hypertension, angina, MI, rate controlling arrhythmias including
AF (by attenuating the SNS), heart failure, thyrotoxicosis, portal
hypertension
Dose:
Hypertension: Propanolol 80mg bd
Adverse Effects: Precipitate asthma, fatigue, coldness of extremities, nightmares
Contraindications:
Asthma, uncontrolled heart filure, bradycardia, hypotension, severe peripheral arterial disease
GTN
Uses:
Angina, LVF, anal fissure
Dose:
Sublingual 0.3 mg prn
Adverse Effects:
Postural hypotension, ↑HR, headache, dizziness
Contraindications:
Hypersensitivity, hypotension, hypertrophic cardiomyopathy, aortic stenosis, cardiac tamponade
Digoxin
Mechanism:
Decreasing the conduction of electrical impulses through the AV node
Uses:
Heart failure, supraventricular arrhythmias
Dose:
Maintenance 500 micrograms daily
Adverse Effects:
Usually excessive dosage: anorexia, nausea, vomiting, diarrhoea, abdominal pain, visual disturbances
Contraindications:
Heart block (because of effect on on AV node), Wolf-Parkinson-White syndrome, VT/VF, hypertrophic cardiomyopathy
Statins
Mechanism:
HMGCoA reductase inhibitor
Uses:
↑Cholesterol, ↑lipids, symptomatic CVS disease (↓risk irrespective of
initial level), asymptomatic prophylaxis of ↑risk CVS disease, consider
in diabetes
Dose:
Simvastatin: 10-40mg od at night
Adverse Effects:
Are rare but include reversible myositis, headache, liver impairment, paraesthesae
Contraindications:
Active liver disease, pregnancy
Amiodarone
Mechanism:
Beta blocker-like and calcium channel blocker-like actions on the SA
and AV nodes, increases the refractory period via sodium- and
potassium-channel effects, and slows intra-cardiac conduction of the
cardiac action potential, via sodium-channel effects.
Uses:
SVT, Refractory VF, haemodynamically stable VT, AF (acutely rhythm conversion, 3rd line for rate control)
Dose:
Oral maintenance. IV infusion (5mg/kg→subsequent given)
Adverse Effects:
Corneal microdeposits (rarely interfere with vision), nausea, vomiting, slate-grey skin discoloration
Contraindications:
Bradycardia, sino-atrial block, thyroid dysfunction.
