Factors affecting the pharmacokinetics of nifedipine

Renwick, A. G.; Vie, J Le; Challenor, V. F.; Waller, Derek G.; Gruchy, BS; George, C. F.

doi:10.1007/bf00543968

Cited by 29 publications

(13 citation statements)

References 24 publications

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“…The difference between the mean and median AUC of NF in Taiwan residents indicates that the data were not normally distributed but skewed. Our data showed significantly higher values of AUC than those for the British [9][10][11][12], Americans [2,15] and Germans [4], but lower than that of Nigerians [10]. No statistical difference was seen when compared with Indians [9], Mexicans [7,16] and Japanese [17] after the NF dose was normalized.…”

Section: Discussioncontrasting

confidence: 74%

“…The mean T 1/2 values for the British reported by Ahsan [9] and Renwick [11] that in our study. Although the British reported in another paper of Renwick [12] and the Japanese [17] also show a mean T 1/2 of around 2.5 h, the sample size was too small to obtain a statistical result. Besides the British and Japanese, the mean T 1/2 values of other reports are all greater than 3 h and show no statistical difference with results of our study.…”

Section: Discussionmentioning

confidence: 76%

“…(II) Possible differences in phenotypes of NF metabolizers may play a role in interethnic distinctions between fast and slow NF metabolizers as well. The pharmacokinetics of NF has been studied in various populations including British [9][10][11][12], Germans [4,13], Americans [2,15], Dutch [14], Nigerians [10], Mexicans [7,16], South Asians [10] and Japanese [17], but not in ethnic Chinese. In this study, a retrospective review was conducted of data from NF bioequivalence studies completed in the past 5 years in Taiwan.…”

Section: Introductionmentioning

confidence: 99%

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Pharmacokinetics of nifedipine in Taiwanese

Chien

Uang

Lin

et al. 2004

Biopharm & Drug Disp

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To elucidate the pharmacokinetics of nifedipine in Taiwanese, a retrospective review of nifedipine bioequivalence studies completed in Taiwan in the past 5 years was conducted. A total of 198 healthy male volunteers were given a single dose of a 10 mg Adalat capsule as a reference drug after overnight fasting. Pharmacokinetic parameters derived from Adalat administration were calculated by non-compartmental analysis with the WinNonlin program. After oral administration of an immediate-release dosage form of a 10 mg nifedipine capsule to Taiwan residents, a skewed distribution with no clear evidence of bimodality of pharmacokinetic parameters was observed. The mean Cmax was 143.12+/-53.48 ng/ml, the mean AUC was 293.77+/-115.62 ng.h/ml, the mean T1/2 was 3.08+/-1.61 h, and the median value of Tmax was 0.61 h. Compared with other published studies, the Cmax and AUC of nifedipine after 10 mg administration were significantly higher in Taiwanese than in British and American subjects. However, the Cmax and AUC were similar to those of Indian and Mexican subjects. According to the antimode of AUC distribution of 22.5 ng.h/ml/mg proposed by Kleinbloesem, 69.7% of Taiwanese can be categorized as slow metabolizers. Based on the results in this study, the majority of Taiwanese show lower activity of nifedipine metabolism.

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Section: Discussioncontrasting

confidence: 74%

Section: Discussionmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

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Pharmacokinetics of nifedipine in Taiwanese

Chien

Uang

Lin

et al. 2004

Biopharm & Drug Disp

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“…An early in vivo study using cimetidine, which is a non‐specific inhibitor of cytochrome P450 isoenzymes, found no interaction with terfenadine [52] despite the fact that it is a good in vivo inhibitor of the metabolism of other substrates of CYP3A, such as nifedipine [53]. Similarly, cimetidine pretreatment did not increase the plasma concentration of ebastine or its active metabolite [54].…”

Section: Interactions With Other Cyp3a Inhibitorsmentioning

confidence: 99%

The metabolism of antihistamines and drug interactions: the role of cytochrome P450 enzymes

Renwick¹

1999

Clin Experimental Allergy

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The non-sedating antihistamines show a diversity of fates in the body and the parent drugs and metabolites may differ in their biological properties. Clinically significant interactions with inhibitors of cytochrome P450 have been reported primarily for terfenadine, which has the potential for cardiac toxicity, and is metabolized to fexofenadine, an antihistamine without cardiac effects. Astemizole shares many of these characteristics and important safety-related interactions are likely. Loratadine undergoes extensive metabolism so that pharmacokinetic interactions could occur, but they would be of little clinical importance because of the lack of cardiac activity of the parent drug and its metabolites. Ebastine also undergoes pharmacokinetic interactions, the significance of which is dependent on clarification of the extent of any relevant cardiotoxicity of both ebastine and its metabolite. Interactions would not be clinically important for cetirizine and fexofenadine which do not show cardiac effects and are eliminated with little metabolism.

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“…When pharmacokinetic data were compared after oral administration of 20 mg nifedipine to healthy volunteers from Germany [9] and Japan [10], the Japanese subjects had significantly higher AUC and Cmax values [11]. Similarly, comparison of AUC data obtained in a number'of studies after the administration of either a single 10 mg capsule or a 20 mg slow release preparation to Caucasians [1, [12][13][14][15][16][17] and Mexican subjects [18][19][20] showed significantly higher AUC and Cmax values in the Mexicans.…”

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confidence: 99%

Factors affecting the absolute bioavailability of nifedipine.

Rashid

Martin

Clarke

et al. 1995

Brit J Clinical Pharma

129

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1. Nifedipine was administered to eight volunteers (seven Caucasian, one East Asian of Chinese origin) as a single 10 mg capsule orally and as 2.5 mg intravenously. The pharmacokinetics were determined under fasting conditions and following 200 ml double strength grapefruit juice taken orally both 2 h before and at the time of dosing. 2. In a separate study, the pharmacokinetics of nifedipine were defined in eight South Asian volunteers (with both parents originating from the Indian subcontinent) following 10 mg nifedipine orally and 2.5 mg intravenously. 3. The administration of grapefruit juice did not alter the pharmacokinetics of intravenous nifedipine, but resulted in a significantly increased area under the plasma concentration‐time curve (AUC) (191 +/‐ 59 c.f. 301 +/‐ 95 ng ml‐1 h, P < 0.05) and bioavailability (0.63 +/‐ 0.18 c.f. 0.86 +/‐ 0.15, P < 0.05) following oral nifedipine. The elimination half‐life was unchanged by administration of grapefruit juice and there was no evidence of decreased formation of the nitropyridine first‐pass metabolite. 4. The AUC of nifedipine after intravenous administration was significantly higher in South Asian subjects than in Caucasians (146 +/‐ 39 c.f. 74 +/‐ 18 ng ml‐1 h, P < 0.002). This was due to a lower systemic clearance in the South Asians which was 50% of that in the Caucasians. The half‐life was markedly prolonged in South Asians (4.1 +/‐ 1.9 c.f. 1.7 +/‐ 0.5 h, P < 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

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Factors affecting the pharmacokinetics of nifedipine

Cited by 29 publications

References 24 publications

Pharmacokinetics of nifedipine in Taiwanese

Pharmacokinetics of nifedipine in Taiwanese

The metabolism of antihistamines and drug interactions: the role of cytochrome P450 enzymes

Factors affecting the absolute bioavailability of nifedipine.

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