verapamil (Isoptin)

see also:

• calcium channel blockers
• calcium channel blocker overdose

• a phenylalkylamine non-dihydropyridine calcium blocking agent
• acts mainly on arteriolar smooth muscle to reduce peripheral vascular resistance as well as having negative inotropic and AV conduction effects

• supraventricular tachycardias (SVT)

• BP < 90mmHg
• the shocked hypotensive patient
• bradycardia
• sick sinus syndrome
• AV block without a pacemaker
• significant left ventricular failure (LVF)
• AF with pre-excitation syndromes including WPW (risk of ventricular fibrillation (VF))
• ventricular tachycardia (VT)
• hypersensitivity
• pregnancy - class C

• concomitant beta adrenergic blockers risk AV blockade
• liver impairment
• grapefruit juice as this is an inhibitor of the CYP-3A4 enzyme and may cause toxicity of verapamil and other calcium channel blockers
• lactation

• hypotension
• negative inotropic effect and cardiac failure risk
• cardiac conduction blockade
• peripheral oedema which is NOT responsive to diuretics which will only cause volume depletion
• constipation
• rarely, myasthenia-like neuromuscular disease
• many possible drug interactions

• 3mg over 1-2min then 1mg per minute as needed up to 10mg max in adults