Losartan

Question 1

Drug class?

Answer 1

Angiotensin Receptor Blockers (ARBs)

Question 2

Mechanism?

Answer 2

Block angiotensin II receptors so have properties similar to ACE inhibitors. But they don’t inhibit the breakdown of bradykinin and other kinins, so are less likely to cause the persistent dry cough.

Question 3

Indications?

Answer 3

Alternative to ACE-I in management of heart failure or diabetic nephropathy.

Question 4

Contra-indications?

Answer 4

• Therapy resistant hypokalaemia or hypercalcaemia
• Severe hepatic impairment; cholestasis and biliary obstructive disorders
• Refractory hyponatraemia
• Symtomatic hyperuricaemia/gout
• 2nd and 3rd trimesters of pregnancy
• Severe renal impairment (i.e. creatinine clearance < 60 ml/min/1.73 m2)

Question 5

Side-effects?

Answer 5

• Hypotension
• Diarrhoea
• Cough

Question 6

Interactions?

Answer 6

• Concomitant use of potassium-sparing diuretics, potassium supplements or salt substitutes containing potassium may lead to increase in serum potassium.
• As with other medicines which affect the excretion of sodium, lithium excretion may be reduced. Therefore, serum lithium levels should be monitored carefully if lithium salts are to be co-administered with ARBs.
• When given with NSAIDs, attenuation of antihypertensive effect may occur.
• In patients with renal impairment being treated with NSAIDs, the co-administration of angiotensin II receptor antagonists may result in a further deterioration of renal function.
• Other substances inducing hypotension like tricyclic antidepressants, antipsychotics, baclofene, amifostine: Concomitant use with these drugs that lower blood pressure, as main or side-effect, may increase the risk of hypotension.