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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-
        tiously.



                                                     (PgDn key for more text)
     Interactions

     * 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.

     References:
     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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