Clinical pharmacology and therapeutics
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Clin. Pharmacol. Ther. · Sep 2010
Randomized Controlled TrialGrapefruit juice greatly reduces the plasma concentrations of the OATP2B1 and CYP3A4 substrate aliskiren.
In a randomized crossover study, 11 healthy volunteers ingested 200 ml of grapefruit juice or water three times a day for 5 days. On day 3, they ingested a single 150-mg dose of aliskiren. Grapefruit juice reduced aliskiren peak plasma concentration (C(max)) by 81% (range, 42-91%, P < 0.001), area under the plasma aliskiren concentration-time curve (AUC)(0-infinity) by 61% (range, 15-72%, P < 0.001), and elimination half-life (t(1/2)) from 26.1 to 23.6 h (P = 0.020). Therefore, concomitant use of aliskiren and grapefruit juice is best avoided.
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Clin. Pharmacol. Ther. · Aug 2010
Randomized Controlled TrialBiological and hemodynamic effects of low doses of fludrocortisone and hydrocortisone, alone or in combination, in healthy volunteers with hypoaldosteronism.
Low doses of hydrocortisone (HC) and fludrocortisone (FC) administered together improve the prognosis after septic shock; however, there continues to be disagreement about the utility of FC for this indication. The biological and hemodynamic effects of HC (50 mg intravenously) and FC (50 microg orally) were assessed in 12 healthy male volunteers with saline-induced hypoaldosteronism in a placebo-controlled, randomized, double-blind, crossover study performed according to a 2 x 2 factorial design. HC and FC significantly decreased urinary sodium and potassium levels (from -58% at 4 h to -28% at 10 h and from -35% at 8 h to -24% at 12 h, respectively) with additive effects. ⋯ At doses used in septic shock, HC induced greater mineralocorticoid effect than FC did. HC also induced transient systemic hemodynamic effects, whereas FC did not. New studies are required to better define the optimal dose of FC in septic shock.
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Clin. Pharmacol. Ther. · Jun 2010
Randomized Controlled TrialThe influence of ondansetron on the analgesic effect of acetaminophen after laparoscopic hysterectomy.
The 5-HT(3) antagonists tropisetron and granisetron have been shown to block the analgesic effect of acetaminophen in healthy volunteers. To study the interaction between ondansetron and acetaminophen in women undergoing laparoscopic hysterectomy, we randomized 134 patients into three groups to receive acetaminophen-placebo (AP), acetaminophen-ondansetron (AO), or placebo-placebo (PP). One gram of intravenous acetaminophen or placebo was administered at the induction of anesthesia and every 6 h thereafter for 24 h, and 4 mg of ondansetron or placebo was administered at the end of surgery. ⋯ Acetaminophen (as compared to placebo) in periodic doses starting at induction of anesthesia reduced the total dosage of oxycodone required over 0-24 h (P = 0.031), but ondansetron given at the end of the surgery had no impact on the analgesic effect of acetaminophen (P = 0.723). The Numeric Rating Scale (NRS) scores for pain were similar whether ondansetron or placebo was administered at the end of the surgery. Therefore, it may be concluded that in women undergoing laparoscopic hysterectomy, the administration of periodic doses of intravenous acetaminophen (as compared to placebo) starting at induction of anesthesia reduces the total dose requirement of oxycodone, and a concomitant dose of a 5-HT(3) antagonist such as ondansetron at the end of the surgery does not block the analgesic effect of acetaminophen.
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Clin. Pharmacol. Ther. · Dec 2009
Randomized Controlled TrialEscitalopram is a weak inhibitor of the CYP2D6-catalyzed O-demethylation of (+)-tramadol but does not reduce the hypoalgesic effect in experimental pain.
Tramadol is O-demethylated to the active metabolite (+)-O-desmethyltramadol ((+)-M1) via CYP2D6, an enzyme that is weakly inhibited by escitalopram. We investigated the possibility of a pharmacokinetic (PK) and pharmacodynamic (PD) effect of escitalopram on tramadol metabolism. Fifteen healthy subjects completed this randomized, double-blind, three-phase, crossover trial. ⋯ The median area under plasma concentration-time curve extrapolated to infinity (AUC(0-infinity)) of (+)-M1 was 2.75 micromol/l.h after placebo pretreatment compared with 1.95 micromol/l.h after escitalopram (P = 0.0027). The mean AUEC(1-12) of CPT were 4,140 and 4,388 cm.s after placebo and escitalopram, respectively (P = 0.71). Although escitalopram is a weak inhibitor of CYP2D6, it does not impair the analgesic effect of tramadol.
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Clin. Pharmacol. Ther. · Oct 2009
Randomized Controlled TrialUse of transdermal melatonin delivery to improve sleep maintenance during daytime.
Oral melatonin (MEL) can improve daytime sleep, but the hormone's short elimination half-life limits its use as a hypnotic in shift workers and individuals with jet lag or other sleep problems. Here we show, in healthy subjects, that transdermal delivery of MEL during the daytime can elevate plasma MEL and reduce waking after sleep onset, by promoting sleep in the latter part of an 8-h sleep opportunity. Transdermal MEL may have advantages over fast-release oral MEL in improving sleep maintenance during adverse circadian phases.