CLINICAL USE

Calcium-channel blocker: Supraventricular arrhythmias Angina Hypertension

DOSE IN NORMAL RENAL FUNCTION

Oral: Supraventricular arrhythmias: 40–120 mg 3 times daily Angina: 80–120 mg 3 times daily Hypertension: 240–480 mg daily in 2–3 divided doses IV: 5–10 mg followed by 5 mg, 5–10 minutes later if required

PHARMACOKINETICS

  • Molecular weight                           : 491.1
  • %Protein binding                           : 90
  • %Excreted unchanged in urine     : <4
  • Volume of distribution (L/kg)       : 3–6
  • half-life – normal/ESRD (hrs)      : 4.5–12/Increased

    DOSE IN RENAL IMPAIRMENT

    GFR (mL/MIN)

  • 20 to 50     : Dose as in normal renal function. Monitor carefully
  • 10 to 20     : Dose as in normal renal function. Monitor carefully
  • <10           : Dose as in normal renal function. Monitor carefully

    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      : Dialysability minimal. Dose as in GFR 10 to 20 mL/min

    IMPORTANT DRUG INTERACTIONS

    Potentially hazardous interactions with other drugs

  • Anaesthetics: increased hypotensive effect
  • Anti-arrhythmics: increased risk of amiodarone-induced bradycardia, AV block and myocardial depression; increased risk of myocardial depression and asystole with disopyramide and flecainide
  • Antibacterials: metabolism increased by rifampicin; metabolism possibly inhibited by erythromycin and clarithromycin (increased risk of toxicity)
  • Anti-epileptics: effect probably reduced by barbiturates, phenytoin and primidone; enhanced effect of carbamazepine Antihypertensives: enhanced hypotensive effect, increased risk of first dose hypotensive effect of post-synaptic alpha- blockers
  • Antivirals: concentration possibly increased by atazanavir and ritonavir
  • Beta-blockers: enhanced hypotensive effect; risk of asystole, severe hypotension and heart failure if co-prescribed with beta-blockers Cardiac glycosides: increased levels of digoxin. Increased AV block and bradycardia
  • Ciclosporin: variable reports of decreased nephrotoxicity and potentiated effect; may also increase ciclosporin levels
  • Grapefruit juice: concentration increased – avoid concomitant use Ivabradine: avoid concomitant use Sirolimus: concentration of both drugs increased Statins: increased myopathy with simvastatin – do not exceed 20 mg of simvastatin.1
  • Tacrolimus: may increase tacrolimus levels Theophylline: enhanced effect of theophylline Verapamil hydrochloride .

    ADMINISTRATION

    Reconstition

    –

    Route

    Oral, IV

    Rate of Administration

    Over 2 minutes (3 minutes in elderly)

    Comments

    –

    OTHER INFORMATION

    Monitor BP and ECG Active metabolites may accumulate in renal impairment

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