Pharmacokinetics of sertraline across pregnancy and postpartum.

Insufficient data inform dosing of antidepressants and clinical monitoring for major depressive disorder (MDD) during the perinatal period. The objectives were to assess the pharmacokinetics of sertraline (SER) across pregnancy and postpartum. Participants treated with SER for MDD underwent serial sampling to measure steady-state concentrations of SER and norsertraline during the second and third trimesters and postpartum (total of 3 assessments). Blood was drawn before observed SER administration and 0.5, 1, 2, 4, 6, 8, 10, 12, and 24 hours after administration. A sensitive high-performance liquid chromatography/mass spectrometric method for simultaneous determination of serum concentrations of SER and norsertraline was developed and validated. For each sampling period for SER, area under the serum concentration versus time curve, maximal serum concentration (Cmax), and the time at which Cmax occurred (Tmax) were determined. Of 11 women initially enrolled, 6 completed second- and third-trimester assessments, and 3 completed all 3 assessments (including the postpartum assessment). Mean changes on all pharmacokinetic parameters were nonsignificant between assessments, although there was a marked heterogeneity among individuals. Results were not significantly altered by incorporation of body weights into the analyses. The range of pharmacokinetic changes between individuals was broad, indicating heterogeneity regarding the impact of pregnancy on SER metabolism. Overall, lowest observed SER area under the curve and Cmax occurred in the third trimester (observed in 5 of 6 participants). Despite nonsignificant mean pharmacokinetic changes, the range of pharmacokinetic changes across pregnancy warrants careful monitoring of depressive symptoms in women with MDD in late pregnancy and further study.

Gender and age differences in medications dispensed from a national chain drugstore.

OBJECTIVES: Our objective was to compare sex and age differences in the medications dispensed in pharmacies from a large national drugstore chain. METHODS: Using a list for the 200 most commonly prescribed medicines, we assessed prescriptions dispensed by a large national chain drug store over 1 year (2002-2003). The analysis used U.S. census data adjusted for the population by sex and age and weighted by the number of pharmacies per state. Results are reported as an odds ratio (OR) of prescriptions dispensed to females and males. RESULTS: Under age 18, 24 drug classes were dispensed more commonly to females (OR > 1) and 18 drug classes more commonly to males (OR < 1). In the 18-24 age group, 48 of 53 drug classes were dispensed more frequently to females. Across other adult groups, females were dispensed more medications than males for 156 of 180 medications. There was greater dispensing to females of antibiotics (OR = 1.74, 95% confidence interval [CI] 1.74-1.74), analgesics (OR = 1.70, 95% CI 1.70-1.70), antihistamines and sympathomimetics (OR = 1.46, 95% CI 1.45-1.46), benzodiazapines (OR = 2.08, 95% CI 2.07-2.08), antidepressants (OR = 2.40, 95% CI 2.39-2.40), diuretics (OR = 1.9328, 95% CI 1.93-1.94), and thyroid drugs (OR = 4.80, 95% CI 4.78-4.82). However, males had higher dispensing of antianginal drugs (OR = 0.84, 95% CI 0.83-0.85), anticoagulants (OR = 0.89, 95% CI 0.88-0.90), glycosides (OR = 0.80, 95% CI 0.79-0.81), and antihypertensives (OR = 0.91, 95% CI 0.91-0.91). More females were dispensed propoxyphene with acetaminophen (OR = 2.23, 95% CI 2.23-2.24), which has been associated with adverse outcomes (hospitalizations, emergency department visits, and deaths). CONCLUSIONS: Females, especially during the reproductive years, are dispensed more medications than males.

Male/female differences in pharmacology: safety issues with QT-prolonging drugs.

For many reasons, information on differences in pharmacokinetics and pharmacodynamics between women and men is limited or lacking altogether. Although women have been included in clinical trials during the past 5-10 years, analyses of the data to address questions in women, men, and various racial/ethnic groups are lacking. Compounding factors are small numbers of women, women not included in early phase clinical trials, and weight or body mass index (BMI) not being considered. Although not much is documented about drug differences between women and men, data from drug adverse events have shown that women more often experience torsades de pointes, a potentially fatal arrhythmia. QT prolongation is considered to be surrogate for torsades because torsades is always preceded by QT prolongation. Drug-induced QT prolongation and accompanying torsades are challenging and urgent safety issues because it is not possible to predict which drugs will induce torsades and which patients are susceptible.

The search for the ideal SERM.

Selective oestrogen receptor modulators (SERMs) are compounds that interact with the oestrogen receptor and have tissue-specific effects distinct from those of oestradiol, acting as an oestrogen agonist in some tissues and as an antagonist in others. The development of SERMs that selectively interact with specific receptors, coactivators and corepressors in different organ systems offers the possibility of improving the risk:benefit profile relative to hormone replacement therapy. Tamoxifen is a SERM that acts as an oestrogen antagonist in breast tissue and is currently being used for the treatment and prevention of breast cancer. Tamoxifen also exhibits oestrogen-agonistic properties in the endometrium and increases the risk of endometrial cancer. Oestrogen and another SERM, raloxifene, have been shown to prevent osteoporosis. The effects of oestrogens on cognitive functions are currently being investigated. Recent data reveal the lack of secondary prevention of coronary heart disease with oestrogen. Oestrogen has been used to treat menopausal symptoms, whereas the SERMs have been shown to induce hot flushes. Current research is focused on producing the ideal SERM, which would have benefits over existing SERMs in terms of preventing cancer, cardiovascular disease, osteoporosis and menopausal symptoms, improving cognitive functions, and have a significantly better toxicity profile in terms of endometrial cancer and thromboembolic events.

Evaluation of warfarin drug interaction listings in US product information for warfarin and interacting drugs.

BACKGROUND: Because interactions with warfarin represent a serious risk to patients, drug information sources used by clinicians should contain accurate, timely, and practical drug interaction information. OBJECTIVE: The aim of this study was to assess the information regarding warfarin interactions that is included in the official labeling of prescription products that interact with warfarin. METHODS: We examined the official labeling information approved by the US Food and Drug Administration for the 50 drugs, biologics, and drug classes that were commonly identified by 3 drug information compendia--Clinical Pharmacology, ePocrates(®), and Micromedex(®)--and the warfarin US prescribing information (PI) as having an interaction with warfarin. The PI of each product was assessed for possible mention of an interaction with warfarin. The data were collected and tabulated by 1 investigator. A clinical investigator evaluated the data for accuracy and consistency. Unresolved issues were discussed with a third investigator and decided by consensus. The interaction listings were compared to determine similarities, differences, and inconsistencies and analyzed by 5 investigators. RESULTS: Of the labeling for 73 products evaluated, 62 (85%) included mention of an interaction with warfarin. Those failing to mention the warfarin interaction were for older generic drugs or influenza vaccine. Among the labels listing an interaction with warfarin, the location of the information, the terminology used, and the inclusion of evidence for the interaction was inconsistent . When considering the PI for all 73 products, Fleiss' kappa coefficient (κ = 0.467) suggested moderate concordance according to the method of Landis and Koch. CONCLUSION: This assessment of official US product labeling for 50 drugs, biologics, and drug classes known to interact with warfarin, comprising 73 distinct agents, found that 15% failed to mention the interaction, even though the interaction was mentioned in the warfarin labeling.

Biologic and molecular mechanisms for sex differences in pharmacokinetics, pharmacodynamics, and pharmacogenetics: Part I.

There are pharmacological differences between women and men that have important clinical consequences. For several drugs, there is a higher incidence in women of drug-induced QT prolongation and a potentially fatal arrhythmia, torsades de pointes. This may be a reflection of the longer baseline QT interval in women. A difference in cardiovascular disease between women and men is that women have a higher mortality rate after myocardial infarction (MI). Women also have a higher rate of hemorrhagic stroke after receiving thrombolytic therapy for an MI. Differences in effectiveness of analgesics have been demonstrated, with kappa opioids providing pain relief for women but not men. Drugs may have different pharmacokinetics in women and men because of differences in phase I and phase II enzymes that metabolize drugs. Conflicting results about biological sex differences have been reported for the major drug metabolizing enzyme, cytochrome P450 3A4 (3A4) and may be related to a role for P-glycoprotein, a cell membrane transporter, reported as two times higher in male livers than those of females. It has been reported that boys need a higher dose of 6-mercaptopurine, which is metabolized by thiopurine methyltransferase (TPMT). TPMT is reported to be 14% higher in male human liver biopsies than those from females. Verapamil, a drug for angina and hypertension, has different clearance and side effects in men and women. Ethnic/racial variations have also been demonstrated with the drug metabolizing enzymes, CYP2C9, 2C19, and 2D6.

Biologic and molecular mechanisms for sex differences in pharmacokinetics, pharmacodynamics, and pharmacogenetics: Part II.

There are specific pharmacology issues related to women's unique physiology, including the hormonal changes that occur throughout their life span. Studies have shown alterations in drug metabolism in relation to phase of menstrual cycle, during pregnancy, or after menopause. In the brain, hormones can alter the response to drugs through various mechanisms. Estrogen and other compounds can bind to the estrogen receptor and modulate a wide range of activities within the cell. In addition, animal studies have demonstrated sexual dimorphism in the brain in terms of both the type of response to estrogen and the response as related to timing of administration. Many normal physiological changes that occur during pregnancy can affect pharmacokinetics and pharmacodynamics. These changes during pregnancy are dramatic rises in levels of estrogen and progesterone, increases in maternal blood volume, altered protein binding resulting from a drop in albumin levels, and a rise in levels of other plasma proteins. The field of chronobiology offers a way to study these changes in biological functions. Chronopharmacology is the study of how biological rhythms, particularly 24-hour, menstrual cycle, and annual rhythms, impact the pharmacokinetics and pharmacodynamics of drugs as a function of their timing. Chronopharmacokinetics is the study of the absorption, distribution, metabolism, and elimination of medicines according to the time of day, menstrual cycle, or year. In addition to applying chronobiology to the study of drugs used in women, new technologies were addressed from computer modeling, pharmacogenetics (genetics of the response to drugs), and in vivo drug metabolism studies.