Calcium antagonists, nitrates, and new antianginal drugs

Thrombolytic treatment and new calcium antagonists

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Nifedipine and cardiopulmonary bypass. Post-bypass management after continuation or withdrawal of therapy

The management of the period after hypothermic cardiopulmonary bypass has been compared in a group of patients maintained on nifedipine therapy, a group who had the drug withdrawn at least 24 hours prior to cardiac surgery, and a control group who had never received calcium antagonists. Patients in the drug withdrawal group were significantly more likely to need vasodilator intervention than the treated (p less than 0.001) or the control (p less than 0.05) groups. Although nifedipine withdrawal appeared to reduce the need for inotropic support, compared to treated (p less than 0.001) and control groups (p less than 0.005), this may be at the cost of increasing systemic vascular resistance. This observation, coupled with reports of a rebound phenomenon following abrupt withdrawal of calcium antagonist therapy, suggests that nifedipine should be continued up to the time of surgery.

Use of inhaled calcium channel blocking agents in the treatment of asthma

The inhalation of drugs that are active in the respiratory tract offers the ideal route of administration, since it results in the rapid delivery of appropriate concentrations with a much reduced risk of systemic adverse effects: Problems with regard to poor absorption from the gastrointestinal tract (sodium cromoglycate) or substantial effect on liver metabolism (verapamil) can be avoided. Certain drugs such as antihistamines and ketotifen may be more effective administered by inhalation since high concentrations with reduced unwanted effects can be achieved on the bronchial surface where, in allergic asthma, the critical initial interaction between sensitized mast cells (mucosal?) and allergen with subsequent mediator release occurs. Indeed inhaled verapamil has been shown to be effective in animal models of asthma but not in man. Systemically administered nifedipine gives partial and variable protection against induced asthma in man and its efficacy (with reduced cardiovascular effects) may well be improved by inhalation.

Nifedipine increases and glyceryl trinitrate decreases apparent liver blood flow in normal subjects

The effects of sublingual nifedipine (10 mg) and of glyceryl trinitrate (500 micrograms), which produce arterial and venous vasodilatation respectively, on indocyanine green estimated apparent liver blood flow (LBF) were studied in six healthy volunteers. Nifedipine significantly increased (33 +/- 12%; mean +/- s.e. mean) and glyceryl trinitrate significantly reduced (18 +/- 3%) LBF. There was a positive relationship (r = 0.92, P less than 0.05) between the reduction in mean arterial pressure produced by nifedipine and the percentage increase in LBF. These results show that single doses of nifedipine and glyceryl trinitrate significantly alter LBF.