The effect of ethinylestradiol-containing contraceptives on the serum concentration of olanzapine and N-desmethyl olanzapine

Drug interactions between hormonal contraceptives and psychotropic drugs: a systematic review

OBJECTIVE

To examine whether the co-administration of hormonal contraceptives (HC) and psychotropic drugs commonly used to treat anxiety and/or depression results in safety or efficacy concerns for either drug.

METHODS

We searched PubMed and Cochrane libraries for clinical or pharmacokinetic (PK) studies that examined co-administration of any HC with psychotropic drugs [selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), oral benzodiazepines, bupropion, mirtazapine, trazadone, buspirone, hydroxyzine, monoamine oxidase inhibitors (MAOIs), or atypical antipsychotics] in reproductive aged women.

RESULTS

Of 555 articles identified, 22 articles (18 studies) met inclusion criteria. We identified 5 studies on SSRIs, four on TCAs, one on bupropion, three on atypical antipsychotics and five on oral benzodiazepines. No articles met inclusion criteria for SNRIs, mirtazapine, trazadone, buspirone, hydroxyzine or MAOIs. Overall, clinical studies did not demonstrate differences in unintended pregnancy rates when HCs were administered with and without psychotropic drugs or in psychotropic drug treatment outcomes when psychotropic drugs were administered with and without HCs. PK studies did not demonstrate changes in drug exposure related to contraceptive safety, contraceptive effectiveness or psychotropic drug effectiveness for most classes of psychotropic drugs. However, limited PK data raise concern for HCs increasing systemic exposure of amitriptyline and imipramine (both TCAs), theoretically posing safety concerns.

CONCLUSION

Limited quality and quantity evidence on use of psychotropic drugs and HCs suggests low concern for clinically significant interactions, though no data exist specifically for non-oral formulations of HC. Given the high frequency of use for both HCs and psychotropic drugs among reproductive-age women in the US, this review highlights a need for further research in this area.

Role of rat cytochromes P450 in the oxidation of 17α-ethinylestradiol

17α-Ethinylestradiol (EE2) is an endocrine disruptor (ED) used as an ingredient of oral contraceptives. Rat hepatic microsomes metabolize EE2 to three products; two of them are hydroxylated EE2 derivatives. Of the hydroxylation reactions, 2-hydroxylation, is the major reaction. Cytochrome P450 (CYP) plays a major role in EE2 hydroxylation. To resolve which rat CYPs are responsible for EE2 oxidation, three approaches were used: induction of specific CYPs, selective inhibition of CYPs, and recombinant rat CYPs. The results demonstrate that EE2 is hydroxylated by several rat CYPs, among them CYP2C6 and 2C11 are most efficient in 2-hydroxy-EE2 formation, while CYP2A and 3A catalyze EE2 hydroxylation to the second product. EE2 is also an inhibitor of CYP2C- and CYP3A-catalyzed hydroxylation of endogenous EDs progesterone and testosterone. EE2 acts as a reversible inhibitor of CYP3A-mediated progesterone 6β-hydroxylation and inactivates CYP3A- and CYP2C-catalyzed testosterone 6β-hydroxylation and progesterone 21- or 16α-hydroxylation, respectively, in a mechanism-based manner.

Meta-analysis: the effects of smoking on the disposition of two commonly used antipsychotic agents, olanzapine and clozapine

OBJECTIVE

To clarify the effects of smoking on the disposition of two commonly used antipsychotics, olanzapine and clozapine, and to create standards to adjust the doses of these drugs in clinical practice based on the smoking status.

DESIGN

A meta-analysis was conducted by searching MEDLINE, Scopus and the Cochrane Library for relevant prospective and retrospective studies.

INCLUDED STUDIES

We included the studies that investigated the effects of smoking on the concentration to dose (C/D) ratio of olanzapine or clozapine.

PRIMARY OUTCOME MEASURE

The weighted mean difference was calculated using a DerSimonian-Laird random effects model, along with 95% CI.

RESULTS

Seven association studies, comprising 1094 patients (652 smokers and 442 non-smokers) with schizophrenia or other psychiatric disorders, were included in the meta-analysis of olanzapine. The C/D ratio was significantly lower in smokers than in non-smokers (p<0.00001), and the mean difference was -0.75 (ng/mL)/(mg/day) (95% CI -0.89 to -0.61). Therefore, it was estimated that if 10 and 20 mg/day of olanzapine would be administered to smokers, about 7 and 14 mg/day, respectively, should be administered to non-smokers in order to obtain the equivalent olanzapine concentration. Four association studies of clozapine were included in the meta-analysis of clozapine, comprising 196 patients (120 smokers and 76 non-smokers) with schizophrenia or other psychiatric disorders. The C/D ratio was significantly lower in smokers than in non-smokers (p<0.00001), and the mean difference was -1.11 (ng/mL)/(mg/day) (95% CI -1.53 to -0.70). Therefore, it was estimated that if 200 and 400 mg/day of clozapine would be administered to smokers, about 100 and 200 mg/day, respectively, should be administered to non-smokers.

CONCLUSIONS

We suggest that the doses of olanzapine and clozapine should be reduced by 30% and 50%, respectively, in non-smokers compared with smokers in order to obtain an equivalent olanzapine or clozapine concentration.

Considering CYP1A2 phenotype and genotype for optimizing the dose of olanzapine in the management of schizophrenia

INTRODUCTION

Schizophrenia, a mental disorder, is a debilitating condition which typically strikes young people in their early 20's. Antipsychotic medications are widely prescribed for the treatment of schizophrenia however a balancing act is necessary to provide the correct dose to each patient. It is suggested that a large number of patients discontinue antipsychotic pharmacotherapy because the treatments provided do not always reduce the positive symptoms of the disease, while many have adverse effects on the patients. This implies that neither the incorrect drug nor the optimal dosage for that patient is achieved.

AREAS COVERED

The current review investigates variability in response to olanzapine with a specific focus on the common intrinsic and extrinsic factors that influence both olanzapine and CYP1A2 activity. Furthermore, the authors discuss the utilization of phenotyping and genotyping of CYP1A2 and their potential utility in clinical practice for olanzapine dosing regimens. The authors also consider the potential of pharmacometrics compared to pharmacogenomics as a tool to personalize medicine.

EXPERT OPINION

Careful consideration must be given to the impact of a genetic variant on the disposition of a drug prior to implementing genetic 'tests' to determine response. CYP1A2 phenotypic assessment can yield important information regarding the disposition of olanzapine; however, it relies on the accuracy of the metric and the minimal impact of other metabolic pathways. The application of pharmacometrics provides an effective method to establish covariates that significantly influence olanzapine disposition which can incorporate phenotype and/or genotype.

Gynecologic and reproductive health concerns of adolescents using selected psychotropic medications

Psychiatric disorders are common in adolescent girls and may require chronic therapies with psychotropic medications. Antipsychotic medications and mood stabilizers have been increasingly prescribed to and widely used by adolescents for a variety of both "on" an "off" label indications. Studies on the safety and monitoring of these medications in adolescent girls have shown important potential for gynecologic and reproductive adverse effects. The objective of this article is to review the mechanisms for and management of menstrual disorders mediated by hyperprolactinemia associated with antipsychotic medications, hypothyroidism associated with lithium and quetiapine, and the independent association of polycystic ovary syndrome (PCOS) in girls using valproic acid. Beyond their susceptibility to these disruptions in the menstrual cycle, adolescent girls with psychiatric illness also have increased sexual risk behaviors. These behaviors makes it all the more important to review teratogenicity and clinically relevant contraceptive drug interactions in adolescent girls using these psychotropic medications.