nifedipine

CLINICAL USE

Calcium-channel blocker:Prophylaxis and treatment of angina Hypertension Raynaud’s phenomenon

DOSE IN NORMAL RENAL FUNCTION

Capsules: 5–20 mg 3 times dailyTablets: 20–40 mg twice dailyMR: 20–90 mg daily

PHARMACOKINETICS

Molecular weight :346.3

%Protein binding :92–98

%Excreted unchanged in urine : <1

Volume of distribution (L/kg) :1.4

half-life – normal/ESRD (hrs) :1.4–11 (depends on preparation)/Unchanged

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function. Start with small doses

<10 : Dose as in normal renal function. Start with small doses

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Not dialysed. Dose as in GFR <10 mL/min

HD :Not dialysed. Dose as in GFR <10 mL/min

HDF/high flux :Unknown dialysability. Dose as in GFR <10 mL/min

CAV/VVHD :Unknown dialysability. Dose as in GFR 10 to 20 mL/min

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Anaesthetics: enhanced hypotensive effect

Antibacterials: metabolism accelerated by rifampicin; concentration increased by quinupristin/dalfopristin

Anti-epileptics: effect reduced by carbamazepine, barbiturates, phenytoin and primidone

Antifungals: metabolism possibly inhibited by itraconazole and ketoconazoleAntihypertensives: enhanced hypotensive effect, increased risk of first dose hypotensive effect of post-synaptic alpha-blockers; occasionally severe hypotension and heart failure with beta-blockers

Antivirals: concentration possibly increased by ritonavirCardiac glycosides: digoxin concentration possibly increased

Ciclosporin: may increase ciclosporin level, but not a problem in practice; nifedipine concentration may be increased

Grapefruit juice: concentration increased – avoid concomitant useInsulin: may impair glucose tolerance Magnesium salts: profound hypotension with IV magnesium

Tacrolimus: increased tacrolimus levels Theophylline: possibly increased theophylline concentration

ADMINISTRATION

Reconstition

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Route

Oral

Rate of Administration

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Comments

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OTHER INFORMATION

Protein binding decreased in severe renal impairmentAcute renal dysfunction reported Increased incidence of side effects (headache, flushing, dizziness and peripheral oedema) in patients with ERFFor acute use, bite capsule then swallow contents with 10–50 mL water.

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