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CALCIUM CHANNEL BLOCKERS : TOXICITY
Adverse Reactions and Overdose Toxicity:
* CV: Peripheral edema (especially with nifedipine), hypoten-
sion, bradycardia (rare with nifedipine), congestive heart
failure. Overdosage can produce marked hypotension and
bradycardia (especially verapamil) and/or conduction block.
* CNS: Dizziness and headache (especially nifedipine), sleep
disturbances, blurred vision.
* GI and metabolic: Nausea (especially nifedipine), constipation
(especially verapamil). Exacerbation of noninsulin-dependent
(Type II) diabetes has been reported.
* Treatment of overdosage: Sympathomimetics and a transvenous
pacemaker may be needed. Parenteral calcium may be tried cau-
(PgDn key for more text)
* CV Depressants: Additive effects on cardiac contractility,
automaticity and AV conduction.
* Pharmacokinetic: Verapamil and possibly nifedipine may in-
crease digoxin blood levels, but the clinical significance of
the effect is minimal.
1. Johnson SM et al: A controlled trial of verapamil for
Prinzmetal's variant angina. N Engl J Med 1981; 304: 862.
2. Lindenberg BS et al: Efficacy and safety of incremental doses
of diltiazem for the treatment of stable angina pectoris. J
Am Coll Cardiol 1983; 2:1129.
3. McAllister RG, Hamann SR, Blouin RA: Pharmacokinetics of
calcium-entry blockers. Am J Cardiol 1985; 55:30B.
4. Muller JE et al: Nifedipine and conventional therapy for un-
stable angina pectoris: a randomized, double-blind com-
parison. Circulation 1984; 69: 728.
5. Weiner DA et al: Efficacy and safety of verapamil in patients
with angina pectoris after 1 year of continuous, high-dose
therapy. Am J Cardiol 1983; 51:1251.
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