Nifedipine dosage

Monitor patients receiving sirolimus or nifedipine in combination with micafungin for sirolimus or nifedipine toxicity, and reduce sirolimus or nifedipine dosage if necessary. 

A patient taking chlorpromazine who was given nifedipine [dosage not stated] for 2 days before snidery, developed marked hypotension during surgery, which was eventually controlled with noradrenaline (norepinephrine). Other phenothiazines and calcium-channel blockers may interact similarly, see Antihypertensives + Other drugs that affect blood pressure , p.880. 

The manufacturers note that the AUC of repeated-dose nifedipine was increased 1.4-fold by quinupristin/dalfopristin, and the maximum level was increased by 1.18-fold. This is probably because quinupristin/dalfopristin inhibits the cytochrome P450 isoenzyme CYP3A4-mediated metabolism of nifedipine. Although the clinical relevance of these increases have not been assessed, the manufacturers advise blood pressure monitoring and, if necessary, a reduction of nifedipine dosage during concurrent use. It is predicted that other calcium-charmel blockers (e.g. verapamil, diltiazem) will also have their levels raised by quinupristin/dalfopristin. ... 

NiFEDiPiNE Individualize dosage. Excessive doses can result in hypotension. 

Increased angina Occasional patients have increased frequency, duration or severity of angina on starting nifedipine or nicardipine or at the time of dosage increases. 

Gengo F, Timko J, D Antonio J, et al Prediction of dosage of lithium carbonate use of a standard predictive method. J Clin Psychiatry 41 319-321, 1980 Geoffroy M, Mogilnicka E, Nielsen M, et al Effect of nifedipine on the shuttlebox escape deficit induced by inescapable shock in the rat. Eur J Pharmacol 154 277-283, 1988... 

Thoma K, Kerker R. Photodegradation and photostabilization of nifedipine in dosage forms. Pharm Ind 1992 54 359-365. 

G. R. Rao, S. Raghuveer, and C. M. R. Srivastava, High pressure liquid chromatographic estimation of nifedipine and its dosage forms, Indian Drugs, 22 435 (1985). 

Comparative pharmacokinetic profiles of nifedipine delivered from Procardia XL, an osmotic pressure-controlled drug delivery system, once-a-day versus that from Procardia, an immediate-release dosage form, taken on time 0, 8 and 16 in human volunteers. Modified from Y.W. Chien. Oral drug delivery and delivery systems. Y.W.Chien (ed.) (1992) Novel Drug Delivery Systems. Marcel Dekker, Inc. New York, pp. 139-196... 

A 30-year-old man required a reduction in lithium dosage from 1500 to 900 mg/day to maintain his serum lithium concentration in the target range shortly after he started to take nifedipine 60 mg/day (645). 

It has been suggested that calcium channel blockers can be used to treat cocaine dependence, and some studies have shown reductions in cocaine-induced subjective and cardiovascular responses with nifedipine and diltiazem. The cardiovascular and subjective responses to cocaine have been evaluated in a double-blind, placebo-controlled, crossover study in five subjects pretreated with two dosage of nimodipine (393). Nimodipine 60 mg attenuated the rise in systolic, but not diastolic, blood pressure after cocaine. In three subjects nimodipine 90 mg produced greater attenuation than 60 mg. The subjective effects of cocaine were not altered by either dose of nimodipine. 

Grundy, J.S. Raheem, K. Foster, R.T. Photostability determination of commercially available nifedipine oral dosage formulations. J. Pharm. Biomed. Anal. 1994, 12 (12), 1529-1535. 

SEDA-22,216). Two confirmations of these observations have been published. In a retrospective study of 103 transplant patients verapamil and diltiazem, but not nifedipine or isradipine, caused a significant increase in plasma ciclosporin concentrations (186). The effect of verapamil and diltiazem on ciclosporin concentrations was independent of dosage. In a crossover comparison between verapamil, felodipine, and isradipine in 22 renal transplant recipients, verapamil interacted... 

A 70-year-old man with hypertension took nifedipine 10 mg bd and 3 months later developed a pruritic eruption on his back, which spread to cover his trunk, limbs, face, and scalp, with involvement of the mouth. His skin deteriorated after the dosage of nifedipine was increased to 20 mg bd 1 year later. Antibodies to the 230 kDa pemphigoid antigen were detected in his serum. His skin improved considerably after withdrawal of nifedipine and the use of topical steroids and oral minocycline. 

Schug BS, Brendel E, Wonnemann M, Wolf D, Wargenau M, Dingier A, Blume HH. Dosage form-related food interaction observed in a marketed once-daUy nifedipine formulation after a high-fat American breakfast. Eur J Clin Pharmacol 2002 58(2) 119-25. 

A retrospective study has shown a significant improvement in kidney function and a 38% reduction in tacrohmus dosage requirements in patients taking both nifedipine and tacrohmus compared to patients not taking nifedipine (115). 

Wang, Z., Hirayama, R, Uekama, K. Design and in vitro evaluation of a modified-release oral dosage form of nifedipine by hybridization of hydroxypropyl-(3-cyclodextrin and hydroxypropyl-cellulose. J. Pharm. Pharmacol. 1993, 45, 942-946. 

There are approximately a dozen calcium channel antagonists marketed in the United States for the treatment of hypertension, certain dysrhythmias, and some forms of angina (see Chaps. 13,15, and 17). The calcium channel blockers are classified by their chemical structure as phenylalkylamines (e.g., verapamil), benzothiapines (e.g., diltiazem), and dihydropyridines (e.g., amlodipine, felodipine, nicardipine, and nifedipine). Several of these agents, namely, diltiazem, nicardipine, nifedipine, and verapamil, are formulated as sustained-release oral dosage forms or have a slow onset of action and longer half-life (e.g., amlodipine " ), allowing once-daily administration. 

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