affected by sex or have a weak tendency toward slower elimination in women. Sex also does not. significantly contribute to the observed free (unbound) fraction of many benzodiazepines, but several reports suggest, higher plasma levels of diazepam in women,104,114 although, again, other reports failed to observe sex dimorphisms in the free fraction of diazepam.108,115 In conclusion then, sex and sex steroid
Inhibitors,research,lifescience,medical levels do not. significantly affect the pharmacokinetics of most, benzodiazepines. For the most, part, any observed differences due to sex, menstrual cycle, or OCs are inconsistent and do not appear to be clinically significant.69,90,103,111,116-120 Finally, studies on benzodiazepine pharmacokinetics tend to be compromised by the small
number of subjects studied and by the failure to control for menopausal status, smoking, and the use of other medications. Antidepressants For most antidepressants, there are no reported sex differences in absorption, particularly Inhibitors,research,lifescience,medical after adjustment for body weight, and surface area.121-q127 Similarly, most, antidepressant studies do not exhibit sex-related differences in distribution, although dothiepin,122 trazodone,124 and bupropion128 may have increased volumes Inhibitors,research,lifescience,medical of distribution in women, suggesting that women would experience lower plasma levels when given the same dose by weight. Elimination appears unaffected by sex for many antidepressants (eg,nefazodone129) and where sex differences Inhibitors,research,lifescience,medical are reported, they are usually only in one variable, ie, clearance or elimination half-life, but. not both.130 Elimination half-life does appear to be increased in women for sertraline131,132 and, less consistently for bupropion.128,133 When one Selleck CP-690550 examines the clinically relevant, measure
– plasma levels – most evidence suggests that sex does not. influence circulating antidepressant levels (eg, nortriptyline, fluvoxamine, moclobemide, maprotiline, and trazodone). Nonetheless, several Inhibitors,research,lifescience,medical studies do suggest, that women experience higher plasma levels of the selective serotonin reuptake inhibitors (SSRIs) fluoxetine and sertraline.132,134 Antipsychotics Few studies have examined the effect of sex on neuroleptic pharmacokinetics. While increased absorption or higher peak concentrations have been observed in old women on ziprasidone, sertindole, and fluphenazine,135-137 confounds, such as OC use, inclusion of outliers, and agedependent phenomena compromise the generalizability of the findings. The metabolism and elimination of some antipsychotic medications (thiothixene, olanzapine, and clozapine) occur more slowly in females than in males, possibly leading to higher drug levels for a given dose, while the elimination of sertindole and ziprasidone is not. sexually dimorphic.135,137-141 While sex differences were identified in sertindole pharmacokinetics, the authors concluded that, these were not clinically relevant.