Polypharmacy Flashcards
How does metformin work?
Reduces hepatic glucose production and increases peripheral glucose utilisation.
Lactic acidosis is a potential but rare risk of metformin. Which patients are at increased risk?
Lactic acidosis is a rare complication which is usually predictable and caused by metformin accumulation when contraindications overlooked (e.g. renal or hepatic impairment, moderate-severe cardiac failure, major illness, surgery, IV radiographic contrast given in renal impairment).
What is the maximum dose of metformin?
1g three times daily
Metformin is contraindicated in patients with an eGFR of …?
= 30
When is digoxin used in patients with heart failure
Digoxin is a second-line drug for patients with heart failure. It is usually used if atrial fibrillation is also present.
What are toxicity effects of digoxin
Significant toxicity (nausea, vomiting, arrhythmias, AV block, confusion).
Digoxin is available in two strength tablets - what are they?
62.5microg and 250microg
How long does it take for a steady state of digoxin to be achieved after initiation or dose change?
When commencing treatment or changing dose it is necessary to wait for 4-5 half lives (5-7 days) for steady state to be reached. Blood should be taken at least 6 hours after the last dose to allow for redistribution.
What electrolyte disturbance is common with ACE inhibitors?
Hyperkalemia
What are potential side effects of sulphonylureas?
Weight gain, hypoglycaemia
What sulphonyureas are preferred in elderly and those with renal impairment?
In the elderly and those with renal impairment short acting (glipizide) and intermediate (gliclazide) sulphonylureas are preferable. Long acting drugs are more likely to cause hypoglycaemia, especially in patients with renal impairment (eg the elderly) because of accumulation of active metabolites.
What percentage of patients taking ACE inhibitors develop cough?
~10%
Renal failure can occur in patients commenced on ACE inhibitors who have ischaemic kidneys. Give some examples of such scenarios.
- Renal artery stenosis
- Hypovolaemia
- Left ventricular failure
What are potential teratogenic effects of ACE inhibitors?
- Intrauterine growth retardation
- Foetal limb contracture
- Craniofacial deformity
- Patent ductus arteriosus
- Hypoplastic lungs
- Renal tubular dysgenesis
- Renal failure
- Oligohydramnios
- Death
What is the annual cost of ACE inhibitor therapy?
$400/yr
Why is captopril rarely used in the long-term management of hypertension?
Short half-life and the need for multiple daily dosing
When may the use of captopril be useful for the management of hypertension?
It may be used to commence patients on an ACE-I if the patient is particularly susceptible to the adverse effects of an ACE-I e.g. underlying renal impairment, on high dose diuretic, aortic stenosis. In these circumstances, they are no less likely to develop these adverse reactions with captopril, but should they occur, it is not going to last as long as with an ACE-I with a longer half life.
Is enalapril better for heart failure or hypertension?
Enalapril has extensive evidence particularly in heart failure, but is not favoured in hypertension as it really should be given twice daily. It is renally cleared.
What is the main disadvantage of perindopril?
The main disadvantage of perindopril is that it comes in 2 different formulations with 2 different sets of doses, which are bioequivalent. To make matters worse you can get the arginine formulation as brand name Coversyl in doses of 2.5, 5 and 10 mg, but if you want to combine it with a thiazide diuretic, (Coversyl Plus) it is only available as the erbumine salt (perindopril 4 mg/indapamide 1.25 mg).
Why is ramipril preferred by some clinicians for treatment of hypertension?
Ramipril is preferred by some clinicians as it has a long half life, and has been proven in a number of different clinical trials. Unfortunately, currently there is a patient premium associated with its use because of its higher price.
What is the duration of action of loop diuretics?
Short duration of action (4 to 6 hours). Hence, they should usually be taken twice a day to maintain naturesis.
What are potential adverse effects of loop diuretics?
- Dehydration
- Hypokalaemia
- Hyponatraemia
- Hyperuricaemia
What are potential adverse effects of NSAIDs?
- Peptic ulcer / GI bleeds
- Renal failure
- Fluid retention
- Cardiovascular complications
How are calcium channel blockers categorised?
Ca channel-blockers are best divided into the more centrally acting verapamil & diltiazem, and the more peripherally acting dihydropyridines (nifedipine, felodipine, lercarnidipine and amlodipine).
