Nifedipine Verapamil

Nifedipine, verapamil, and diltiazem are all efficacious in the treatment of mild and moderate hypertension, but nifedipine is more efficacious than diltiazem and verapamil in the control of severe hypertension. Nifedipine does not cause significant reflex tachycardia or orthostatic hypotension. Nifedipine benefits the older and black patients and patients with low PRA. 

Despite the growth in interest in calcium blockers, there are comparatively few calcium channel blocking agents currently in clinical use. These drugs are characterised by the fact that they belong to classes of compounds which are chemically unrelated like Diltiazem , Nifedipine , Verapamil , Fluspirilene and some others (Scheme 1). 

Because calcium channel antagonists may be more effective, have few serious adverse effects, and can be given less frequently than nitrates, some authorities consider them the agents of choice for variant angina. Nifedipine, verapamil, and diltiazem are all equally effective as single agents for... 

Anxiolytics clonazepam, diazepam, temazepam, triazolam, alprazolam, midazolam, buspirone Anticonvulsants ethosuximide, carbamazepine Calcium channel blockers diltiazem, felodipine, nifedipine, verapamil... 

Calcium channel blockers (eg, diltiazem, nifedipine, verapamil). 

Alcohol, antidepressants, hypnotics, sedatives, tranquillizers, fenfluramine, levodopa, vasodilators such as nitrates, nifedipine, verapamil Potentiation. 

Verapamil, diltiazem, and perhaps nicardipine (but not nifedipine) inhibit hepatic drug-metabolizing enzymes. Metabolism of diltiazem, nifedipine, verapamil, and probably other calcium channel blockers subject to induction and inhibition. 

Cyt 3A3/4 metabolizes clozapine, sertindole, quetiapine common substrates -tricyclic antidepressants, nefazodone, sertraline, carbamazepine, ethosuximide, terfenadine, benzodiazepines, diltiazem, nifedipine, verapamil, erythromycin, cyclosporine, lidocaine, quinidine, cisapride, paracetamol. Common inhibitors -nefazodone, fluvoxamine, fluoxetine, ketoconazole. 

Drugs metabolized by CYP that interact with cimetidine include, but are not limited to, the following lidocaine, quinidine, midazolam, triazolam, nifedipine, verapamil, and fentanyl (4). In each instance, inhibition of CYP by cimetidine results in reduced metabolic clearance and increases in serum concentrations of the other drug, which can lead to the expected toxicity and adverse experiences characteristic of the other drug. 

Figure 7.12 Diagrammatic representation of cross section of calcium channel showing various sites that bind drugs and toxins. Bay K 8644, atrotoxin and maitotoxin are agonists (activators) of calcium channels. Nifedipine, verapamil, and diltiazem are antagonists (blockers) of calcium channels. (From Eldefrawi, M.E. and Eldefrawi, A.T., in Safe Insecticides Development and Use, Hodgson, E. and Kuhr, R.J., Eds., Marcel Dekker, New York, 1990, p. 155. With permission.)...

Interactions concomitant i.v. administration of a calcium channel blocker that affects conduction (verapamil, diltiazem) increases the risk of bradycardia and AV block. In patients with depressed myocardial contractility, the combination of oral or i.v. p-blockade and calcium chaimel blockade (nifedipine, verapamil) may cause hypotension or cardiac failure. 

Nifedipine, verapamil, and diltiazem have aU been implicated as possible causes of erythema multiforme and its variants, Stevens-Johnson syndrome and toxic epidermal necrolysis, and/or exfoliative dermatitis from FDA data (112). 

Mexiletine Progesterone Testosterone Sildenafil Trazodone Vineristine Zaleplon Zolpidem Amlodipine Diltiazem Nifedipine Verapamil... 

Nifedipine, verapamil, and diltiazem are all equally effective as single agents for the initial management of variant angina and... 

CCBs decrease contractility and increase vasodilation by preventing the influx of Ca2+ required for muscle contraction. The sequence of readions involved is summarized in Figure 111-5-2. The CCBs considered are the dihydropyridines (e.g., nifedipine), verapamil, diltiazem, and bepridil. 

Smooth Muscle. All known calcium inhibitory compounds decrease smooth muscle tone in both the coronary and peripheral circulations (11 , 114, 115, 140, 145-147). Comparative studies using dogs suggest that this effect varies in intensity but surpasses negative inotropic activity (114, 145). Nifedipine, verapamil and perhexiline exhibit their most pronounced vasodilator effects upon femoral arterial blood flow followed by coronary, renal, and mesenteric beds (44, 47,... 

Contrast the sympatholytic effect of nifedipine, verapamil and diltiazem. 

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