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  1. Comparison of propofol and methohexitone as an induction agent in anaesthesia for electroconvulsive therapy
    Lim SK, Lim WL, Elegbe EO
    West Afr J Med, 1996 Oct-Dec;15(4):186-9.
    PMID: 9020593
    30 patients who received electroconvulsive therapy were anaesthetized with either Propofol or Methohexitone in a randomized cross-over study. Recovery times were shorter in those who received Propofol. The decrease in diastolic pressure after induction was greater with Propofol than with Methohexitone. There was a greater increase in the blood pressure after the electroconvulsive therapy in those who received Methohexitone. The duration of convulsion was similar for both agents.
    Matched MeSH terms: Cross-Over Studies
  2. Trans (elaidic) fatty acids adversely affect the lipoprotein profile relative to specific saturated fatty acids in humans
    Sundram K, Ismail A, Hayes KC, Jeyamalar R, Pathmanathan R
    J Nutr, 1997 Mar;127(3):514S-520S.
    PMID: 9082038
    Although dietary trans fatty acids can affect plasma lipoproteins negatively in humans, no direct comparison with specific saturated fatty acids has been reported, even though trans fatty acids were designed to replace saturates in foods and food processing. In this study, dietary trans 18:1 [elaidic acid at 5.5% energy (en)] was specifically exchanged for cis 18:1, 16:0 or 12:0 + 14:0 in 27 male and female subjects consuming moderate fat (31% en), low cholesterol (<225 mg/d) whole food diets during 4-wk diet periods in a crossover design. The trans-rich fat significantly elevated total cholesterol and LDL cholesterol relative to the 16:0-rich and 18:1-rich fats and uniquely depressed HDL cholesterol relative to all of the fats tested. Trans fatty acids also elevated lipoprotein (a) [Lp(a)] values relative to all dietary treatments. Furthermore, identical effects on lipoproteins were elicited by 16:0 and cis 18:1 in these subjects. The current results suggest that elaidic acid, one of the principal trans isomers produced during industrial hydrogenation of edible oils, adversely affects plasma lipoproteins. Thus, the negative effect of elaidic acid on the lipoprotein profile of humans appears to be unmatched by any other natural fatty acid(s).
    Matched MeSH terms: Cross-Over Studies
  3. Bioavailability and pharmacokinetics of acyclovir tablet preparation
    Yuen KH, Peh KK, Billa N, Chan KL, Toh WT
    Drug Dev Ind Pharm, 1998 Feb;24(2):193-6.
    PMID: 15605452
    The bioavailability of a generic preparation of acyclovir (Avorax) was compared with the innovator product, Zovirax. Twelve healthy volunteers participated in the study, conducted according to a randomized, two-way crossover design. The preparations were compared using the parameters area under the plasma concentration time curve (AUC(0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (Tmax). No statistically significant difference was observed between the Tmax or the logarithmic transformed AUC(0-infinity) and C(max) values of the two preparations. In addition, the 90% confidence interval for the ratio of the logarithmic transformed AUC(0-infinity) values of Avorax over those of Zovirax was found to lie between 0.85 and 1.06, while that of the logarithmic transformed Cmax values was between 0.95 and 1.25, being within the bioequivalence limit of 0.80-1.25. Moreover, the elimination rate constant (k(e)), elimination half-life (t(1/2)), and apparent volume of distribution (Vd) values obtained with the two preparations were comparable and not significantly different statistically.
    Matched MeSH terms: Cross-Over Studies
  4. Comparative pharmacokinetic study of oral and rectal formulations of artesunic acid in healthy volunteers
    Navaratnam V, Mansor SM, Mordi MN, Akbar A, Abdullah MN
    Eur J Clin Pharmacol, 1998 Jul;54(5):411-4.
    PMID: 9754985
    OBJECTIVE: A single cross-over, comparative pharmacokinetic study of oral and rectal formulations of 200 mg artesunic acid in 12 healthy Malaysian volunteers is reported.

    METHODS: Plasma concentrations of artesunic acid and dihydroartemisinin were determined simultaneously by HPLC with electrochemical detection. The test drug was well tolerated and no undesirable adverse effects were observed.

    RESULTS: Comparison of pharmacokinetic parameters of artesunic acid after oral and rectal administration showed statistically significant differences in t(max) and AUC, with no changes for Cmax and t1/2. As for dihydroartemisinin, differences were observed for t(max) and Cmax but not for AUC.

    CONCLUSION: There appear to be pharmacokinetic differences between oral and rectal modes of administration. The significance of these findings should be explored in malaria patients before appropriate therapeutic regimens are devised.

    Matched MeSH terms: Cross-Over Studies
  5. Pharmacokinetic and bioequivalent study of a generic Metoprolol tablet preparation
    Yuen KH, Peh KK, Chan KL, Toh WT
    Drug Dev Ind Pharm, 1998 Oct;24(10):955-9.
    PMID: 9876550
    A study was conducted to compare the in vivo bioavailability of a generic metoprolol tablet preparation (Metoprolol) with that of the innovator product, Betaloc. Both preparations have a labeled dose of 100 mg metoprolol tartrate. Twelve healthy adult male volunteers participated in the study, which was conducted according to a standard two-way crossover design with a washout period of 1 week. The bioavailability was compared using the total area under the plasma level versus time curve (AUC0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (Tmax). No statistically significant difference was observed between the logarithmically transformed AUC0-infinity values or the logarithmically transformed Cmax values of the two preparations. However, a statistically significant difference was observed between the Tmax values, but may not be therapeutically significant or important. Moreover, the 90% confidence interval (CI) for the ratio of the logarithmically transformed AUC0-infinity values of Metoprolol over those of Betaloc was calculated to be between 0.94 and 1.02, while that of Cmax was between 0.98 and 1.01, both of which are within the acceptable limit of 0.80-1.25. From the data obtained, it was also observed that a high proportion of our volunteers of Asian origin appeared to be poor metabolizers of metoprolol, which was consistent with what had been observed in our previous study of another preparation of metoprolol.
    Matched MeSH terms: Cross-Over Studies
  6. Addition of inhaled salmeterol to inhaled corticosteroids in patients with poorly controlled nocturnal asthma
    Norhaya MR, Yap TM, Zainudin BM
    Respirology, 1999 Mar;4(1):77-81.
    PMID: 10339734 DOI: 10.1046/j.1440-1843.1999.00153.x
    The effect of adding inhaled salmeterol to inhaled corticosteroids was studied in patients with poorly controlled nocturnal asthma. In a double-blind, cross-over study, 20 patients were randomized to receive either salmeterol 50 micrograms twice daily or placebo via a Diskhaler after a 1-week run-in period. After 4 weeks of treatment, patients were subsequently crossed over to receive the other treatment for a further 4 weeks with a 2-week wash-out period in between. The response to treatment was assessed by peak expiratory flow rates (PEF) measured in the morning and evening, symptom scores of asthma, number of bronchodilators used, forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) at regular intervals. Patients' preference for the Diskhaler or metered-dose inhaler was assessed at the last visit. The results showed that morning PEF was significantly higher while on salmeterol than on placebo (296.9 +/- 70.2 vs 274.6 +/- 77.4 L/min). Evening PEF showed a trend towards a higher value while on salmeterol than on placebo (321.1 +/- 73.4 vs 288.7 +/- 79.4 L/min), but the difference was not significant. There was no statistically significant improvement in symptom scores, number of rescue bronchodilators used and FEV1 or FVC between the two treatment groups. The occurrence of side effects in terms of tremors and palpitations between treatment and placebo were similar. There were more patients who preferred Diskhaler to metered-dose inhaler (70% vs 30%). We conclude that salmeterol 50 micrograms twice daily produces significant improvement in morning PEF and is well tolerated in patients with nocturnal asthma. Diskhaler is a device which is easy to use and preferred to a metered-dose inhaler.
    Study site: Respiratory Clinic, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
    Matched MeSH terms: Cross-Over Studies
  7. Comparative bioavailability study of two atenolol tablet preparations
    Peh KK, Yuen KH, Wong JW, Toh WT
    Drug Dev Ind Pharm, 1999 Mar;25(3):357-60.
    PMID: 10071830
    A study was conducted to compare the bioavailability of a generic product of atenolol (Normaten FC) with the innovator product, Tenormin. Twelve healthy adult volunteers participated in the study conducted according to a randomized, two-way crossover design. The preparations were compared using area under the plasma concentration-time curve AUC0-infinity, peak plasma concentration Cmax, and time to reach peak plasma concentration Tmax. No statistically significant difference was obtained between the Tmax values and the logarithmic transformed AUC0-infinity and Cmax values of the two products. Moreover, the 90% confidence interval for the ratio of the logarithmically transformed AUC0-infinity values of Normaten FC over those of Tenormin was found to lie between 0.82 and 0.98, while that of the logarithmically transformed Cmax values was between 0.82 and 1.09, both being within the bioequivalence limit of 0.80-1.25. The values of elimination half-life t1/2 between the two products were also found comparable and not significantly different statistically. The t1/2 values obtained in our study were slightly longer than those reported in the literature for other population groups.
    Matched MeSH terms: Cross-Over Studies
  8. Comparative bioavailability study of a generic naltrexone tablet preparation
    Yuen KH, Peh KK, Billa N
    Drug Dev Ind Pharm, 1999 Mar;25(3):353-6.
    PMID: 10071829
    The bioavailability of a generic preparation of naltrexone (Narpan) was compared with the innovator product, Trexan. Twelve healthy volunteers participated in the study, conducted according to a completely randomized, two-way crossover design. The preparations were compared using the parameters area under the plasma concentration-time curve AUC0-infinity, peak plasma concentration Cmax, and time to reach peak plasma concentration Tmax. No statistically significant difference was observed between the logarithmic transformed AUC0-infinity and the logarithmically transformed Cmax values of the two preparations. Also, no statistically significant difference was observed between the untransformed Tmax values. In addition, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values of Narpan over those of Trexan was found to lie between 0.87 and 1.01, while that of the logarithmic transformed Cmax values was between 0.94 and 1.23, both being within the bioequivalence limit of 0.80-1.25. The numerical values of the elimination half-life (t1/2) obtained with the two preparations were also not significantly different and were comparable to those reported in the literature.
    Matched MeSH terms: Cross-Over Studies
  9. Relating in vitro/in vivo data of two controlled-release metformin formulations
    Yuen KH, Peh KK, Tan BL
    Drug Dev Ind Pharm, 1999 May;25(5):613-8.
    PMID: 10219530
    This study was conducted to compare the bioavailability of two controlled-release metformin preparations (Diabetmin Retard and Glucophage Retard) and also to correlate the in vitro and in vivo data obtained with the two preparations. Twelve healthy volunteers participated in the study, conducted according to a completely randomized, two-way crossover design. The preparations were compared using area under the plasma concentration-time curve AUC0-infinity, time to reach peak plasma concentration Tmax, and peak plasma concentration Cmax, while correlation was determined between in vitro release and in vivo absorption. Diabetmin Retard demonstrated a slower rate of in vitro release, but a faster rate of in vivo absorption than Glucophage Retard. However, the in vivo absorption of both products was found to be slower than that of drug released in vitro. A satisfactory relationship could be established between the in vitro and in vivo results, but there was no rank order correlation. No statistically significant difference was observed between the two preparations in the parameters AUC0-infinity and Cmax. However, a slight but statistically significant difference was observed between the Tmax values, but it may not be therapeutically significant. Moreover, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values, as well as the logarithmic transformed Cmax values, of Diabetmin Retard over those of Glucophage Retard was within the acceptance criteria of 0.80-1.25.
    Matched MeSH terms: Cross-Over Studies
  10. Bioequivalence of a generic metformin tablet preparation
    Yuen KH, Wong JW, Billa N, Julianto T, Toh WT
    Int J Clin Pharmacol Ther, 1999 Jul;37(7):319-22.
    PMID: 10442505
    The bioavailability of a generic preparation of metformin (Diabetmin from Hovid Sdn Bhd) was evaluated in comparison with a proprietary product (Glucophage from Lipha Pharma Ltd., UK).
    Matched MeSH terms: Cross-Over Studies
  11. Fulltext Comparative bioavailability study of two ketoconazole tablet preparations
    Yuen KH, Wong JW, Billa N, Choy WP, Julianto T
    Med J Malaysia, 1999 Dec;54(4):482-6.
    PMID: 11072466
    The bioavailability of a generic preparation of ketoconazole (Zorinax from Xepa-Soul Pattinson, Malaysia) was evaluated in comparison with the innovator product (Nizoral from Janssen Pharmaceutica, Switzerland). Eighteen healthy male volunteers participated in the study conducted according to a two-way crossover design. The bioavailability was compared using the parameters, total area under the plasma concentration-time curve (AUC0-infinity), peak plasma concentration (Cmax) and time to reach peak plasma concentration (Tmax). No statistically significant difference was observed between the values of the two products in all the three parameters. Moreover, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity and Cmax values of Zorinax over Nizoral was found to lie between 0.82-1.04 and 0.83-1.02, respectively, being within the acceptable equivalence limit of 0.80-1.25. These findings indicate that the two preparations are comparable in the extent and rate of absorption. In addition, the elimination rate constant (ke) and apparent volume of distribution (Vd) were calculated. For both parameters, there was no statistically significant difference between the values obtained from the data of the two preparations. Moreover, the values are comparable to those reported in the literature.
    Matched MeSH terms: Cross-Over Studies
  12. Improved bioavailability of vitamin E with a self emulsifying formulation
    Julianto T, Yuen KH, Noor AM
    Int J Pharm, 2000 Apr 25;200(1):53-7.
    PMID: 10845685
    A single dose study was conducted to evaluate the bioavailability of a novel self-emulsifying vitamin E preparation, in comparison with that of a commercial product, Natopherol, available as soft gelatin capsules under fasted condition. The self-emulsifying preparation achieved a faster rate and higher extent of absorption. A statistically significant difference was observed between the values of the two preparations in the parameters AUC, Cmax and Tmax. Moreover, the 90% confidence interval of the logarithmic transformed AUC values of the self-emulsifying preparation over those of the soft gelatin capsule product was found to be between 2.1 and 4.1, suggesting an increase in bioavailability of between 210 and 410%. As for Cmax, the 90% confidence interval was between 2.1 and 3.0. However, no statistically significant difference was observed between the t(1/2) values estimated from the plasma concentration versus time data of the two preparations. The values are also comparable to those reported in the literature.
    Matched MeSH terms: Cross-Over Studies
  13. Comparative bioavailability study of two controlled-release pentoxifylline tablet preparations
    Yuen KH, Wong JW, Peh KK, Julianto T, Choy WP
    Drug Dev Ind Pharm, 2000 Jul;26(7):803-7.
    PMID: 10872103
    The bioavailability of a generic preparation of pentoxifylline sustained-release (SR) tablet was evaluated in comparison with a proprietary product (Trental 400). For the study, 12 healthy male volunteers participated; the study was conducted according to a randomized, two-way crossover design. The bioavailability was compared using the parameters total area under the plasma level-time curve AUC0-infinity, peak plasma concentration Cmax, and time to reach peak plasma concentration Tmax. No statistically significant difference was observed between the values of the two products in all three parameters. The 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values of the generic pentoxifylline over those of Trental 400 was found to lie between 0.83 and 1.00, while that of the parameter Cmax was between 0.91 and 1.29. In addition, elimination half-life t1/2 and apparent volume of distribution Vd were calculated. There was no statistically significant difference between the t1/2 Vd values obtained from the data of the two preparations.
    Matched MeSH terms: Cross-Over Studies
  14. Efficacy and safety of single versus multiple daily doses of glibenclamide in type 2 diabetes mellitus
    Wan Mohamad WB, Tun Fizi A, Ismail RB, Mafauzy M
    Diabetes Res Clin Pract, 2000 Aug;49(2-3):93-9.
    PMID: 10963819 DOI: 10.1016/s0168-8227(00)00138-8
    Although long acting, glibenclamide is frequently given in split doses for type 2 diabetes mellitus. This may discourage compliance. It is thus appropriate to consider dosing it less frequently. We therefore studied glibenclamide effects when used once daily and when used in split doses. Our objective was to assess the feasibility of using once daily dosing as a regimen of choice. We measured plasma glucose, insulin, glibenclamide, lipids, HbAl and body mass index associated with the regimens. We also compared the number of hypoglycemic episodes occurring with them. Thirty type 2 diabetics on multiple daily glibenclamide were enrolled. Their regimens were changed over to once daily. Blood for glucose, insulin, lipids, HbAl and glibenclamide and body weight measurements were determined before and after the crossover period. We found no major difference in the sugar and insulin profiles with the two regimens. Fasting total cholesterol and triglyceride were also similar and so were plasma glibenclamide. The HbAl levels and body mass index and number of minor and major hypoglycemic episodes and hospital admissions for hypoglycemia also did not differ. We conclude that single daily dosing of glibenclamide was equivalent to multiple daily dose regimens. It can be used to an advantage to improve patient's compliance.
    Matched MeSH terms: Cross-Over Studies
  15. The effects of angiotensin II on pulse wave velocity in healthy humans
    Rehman A, Rahman AR, Rasool AH, Naing NN
    Int J Clin Pharmacol Ther, 2001 Oct;39(10):423-30.
    PMID: 11680667
    To examine the dose response relationship between Ang II and pulse wave velocity (an index of arterial stiffness) in healthy human volunteers.
    Matched MeSH terms: Cross-Over Studies
  16. Improved oral bioavailability of artemisinin through inclusion complexation with beta- and gamma-cyclodextrins
    Wong JW, Yuen KH
    Int J Pharm, 2001 Oct 04;227(1-2):177-85.
    PMID: 11564552
    The bioavailability of beta- and gamma-cyclodextrin artemisinin complexes was evaluated in comparison with a normal commercially available preparation, Artemisinin 250. Twelve healthy male volunteers participated in the study conducted according to a three-way crossover design. The bioavailability was compared using the parameters, total area under the plasma level-time curve (AUC(0-infinity)), peak plasma concentration (C(max)), and time to reach peak plasma concentration (T(max)). A statistically significant difference was observed between the values of the complexes and Artemisinin 250 for the three parameters. However, no statistically significant difference was observed between the values of the beta- and gamma-cyclodextrin complexes. Moreover, the 90% confidence interval for the ratio of the AUC(0-infinity) values of the beta-cyclodextrin complex over those of Artemisinin 250 was estimated to be between 1.51-2.04, while that of C(max) was between 1.73-2.93. For the gamma-cyclodextrin complex, the respective intervals were 1.30-1.76 and 1.43-2.43. These findings indicated that the beta- and gamma-cyclodextrin complexes had a much higher rate and extent of bioavailability compared to Artemisinin 250. In addition, the absorption of artemisinin was observed to be poor and negligible when the preparations started to arrive in the colon. This could be attributed to poor dissolution of artemisinin in the semi-solid faecal matter in the lower part of the gastrointestinal tract.
    Matched MeSH terms: Cross-Over Studies
  17. Effect of angiotensin II on pulse wave velocity in humans is mediated through angiotensin II type 1 (AT(1)) receptors
    Rehman A, Rahman AR, Rasool AH
    J Hum Hypertens, 2002 Apr;16(4):261-6.
    PMID: 11967720
    The objective of this study was to examine the effect of angiotensin II (Ang II) and angiotensin II type 1 (AT(1)) receptor blockade on pulse wave velocity (PWV) in healthy humans. We studied nine young male volunteers in a double-blind randomised crossover design. Carotid-femoral PWV (an index of arterial stiffness) was measured by using a Complior machine. Subjects were previously treated for 3 days with once-daily dose of either a placebo or valsartan 80 mg. On the third day, they were infused with either placebo or 5 ng/kg/min of Ang II over 30 min. Subjects thus received placebo capsule + placebo infusion (P), valsartan + placebo infusion (V), placebo + Ang II infusion (A), and valsartan + Ang II infusion (VA) combinations. Heart rate (HR), blood pressure and PWV were recorded at baseline and then every 10 min during infusion and once after the end of infusion. There were significant increases in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) with A compared with P (P = 0.002, P = 0.002, P = 0.001 respectively). These rises in blood pressure were completely blocked by valsartan. A significant rise in PWV by A was seen compared with P (8.38 +/- 0.24 vs 7.48 +/- 0.24 m/sec, P = 0.013) and was completely blocked by valsartan; VA compared with P (7.27 +/- 0.24 vs 7.48 +/- 0.24 m/sec, P = NS). Multiple linear regression analysis showed that blockade of Ang II induced increase in blood pressure by valsartan contributed to only 30% of the total reduction in Ang II induced rise in PWV (R(2) = 0.306). The conclusions were that valsartan completely blocks the effect of Ang II on PWV. The effect of Ang II on PWV is mediated through AT(1)receptors. Reduction in PWV by Ang II antagonist is not fully explained by its pressure lowering effect of Ang II and may be partially independent of its effect on blood pressure.
    Matched MeSH terms: Cross-Over Studies
  18. A comparative study of sevoflurane sedation with nitrous oxide sedation for dental surgery
    Wang CY, Chiu CL, Har KO, Chan C, Rahman ZA
    Int J Oral Maxillofac Surg, 2002 Oct;31(5):506-10.
    PMID: 12418566
    This study compares the use of inhalation sedation using sevoflurane (group S) with inhalation sedation using nitrous oxide (group N) in patients undergoing bilateral extraction of third molar teeth under local anaesthesia. The study was designed as a cross-over study. Seventeen ASA I, day surgery patients were studied. Patients were randomly allocated to receive either 8 l/min 50% nitrous oxide in oxygen (group N) or same flow of 1% sevoflurane (group S) for the first procedure. Each patient then had the alternate method of sedation for the second procedure. There were no significant differences between the methods in patient co-operation and surgeon's satisfaction with sedation. Psychomotor tests were comparable in both groups. The patients were significantly more sedated in the group S compared to group N (P=0.004). Significantly more patients complained of an unpleasant odour group S (P<0.01) but none withdrew from the study for this reason. No adverse cardiorespiratory effects resulted from sevoflurane or nitrous oxide sedation. Both methods gave good amnesia during the procedure. There was high acceptance of both methods and the patients rated the technique as equally satisfactory. We conclude that inhalation sedation with sevoflurane is a suitable alternative method to nitrous oxide sedation.
    Matched MeSH terms: Cross-Over Studies
  19. Influence of route of administration on the absorption and disposition of alpha-, gamma- and delta-tocotrienols in rats
    Yap SP, Yuen KH, Lim AB
    J Pharm Pharmacol, 2003 Jan;55(1):53-8.
    PMID: 12625867
    A study was conducted to evaluate the bioavailability of alpha-, gamma- and delta-tocotrienols administered via oral, intravenous, intramuscular and intraperitoneal routes in rats. Three separate experiments, each conducted according to a two-way crossover design, were carried out to compare intravenous and oral, intramuscular and oral, and intraperitoneal and oral administration. Oral absorption of all three tocotrienols was found to be incomplete. Of the three tocotrienols, alpha-tocotrienol had the highest oral bioavailability, at about 27.7+/-9.2%, compared with gamma- and delta-tocotrienols, which had values of 9.1+/-2.4% and 8.5+/-3.5%, respectively. Such biodiscrimination was also observed in their total clearance rates (estimated from the intravenous data). alpha-Tocotrienol showed the lowest clearance rate at about 0.16 L kg(-1) h(-1), whereas that of delta- and gamma-tocotrienols was quite similar, with values of 0.24 and 0.23 L kg(-1) h(-1), respectively. Interestingly, all three tocotrienols were found to be negligibly absorbed when administered intraperitoneally and intramuscularly. Thus, these two routes of administration should be avoided when evaluating the biological activities of the tocotrienols in whole animal experiments.
    Matched MeSH terms: Cross-Over Studies
  20. Evidence of an interaction between nifedipine and nafcillin in humans
    Lang CC, Jamal SK, Mohamed Z, Mustafa MR, Mustafa AM, Lee TC
    Br J Clin Pharmacol, 2003 Jun;55(6):588-90.
    PMID: 12814453
    AIMS: Nafcillin (Wyeth Laboratories, Philadelphia, PA, USA) has been reported to induce the metabolism of cyclosporin and warfarin, which are known substrates of cytochrome P-450 (CYP). However, there has not been any report to date on its possible interaction with nifedipine, an index substrate of the enzyme, CYP3A4.

    METHODS: Nine healthy normotensive subjects participated in this randomized placebo-controlled two-way crossover study examining the effects of 5 days' pretreatment of nafcillin 500 mg or placebo four times daily on the pharmacokinetics of an oral dose of nifedipine 10 mg. Plasma nifedipine concentrations were measured by gas chromatography-mass spectro.

    RESULTS: The area under the plasma nifedipine concentration-time curve (AUC0-alpha) in nafcillin-pretreated subjects (80.9 +/- 32.9 micro g l-1 h-1) was significantly decreased compared with subjects who received only nifedipine (216.4 +/- 93.2 micro g l-1 h-1) (P < 0.001). Total plasma clearance of nifedipine (CL/F) was significantly increased with nafcillin pretreatment (138.5 +/- 42.0 l h-1 vs 56.5 +/- 32.0 l h-1) (P < 0.002).

    CONCLUSIONS: The results show that nafcillin pretreatment markedly increased the clearance of nifedipine and suggest that nafcillin is a potent inducer of CYP enzyme.

    Matched MeSH terms: Cross-Over Studies
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