Background Pharmacokinetic (PK) parameters based on short sampling times (48 h or less) may contain inaccuracies due to their dependency on extrapolated values. This study was designed to measure PK parameters with greater accuracy in obese users of a low-dose oral contraceptive (OC), and to correlate drug levels with assessments of end-organ activity. Study design Obese (BMI ≥30 kg/m2), ovulatory, otherwise healthy, women (n = 32) received an OC containing 20 mcg ethinyl estradiol (EE)/100 mcg levonorgestrel (LNG) for two cycles. EE and LNG PK parameters were characterized for 168 h at the end of Cycle 1. During Cycle 2, biweekly outpatient visits were performed to assess cervical mucus, monitor ovarian activity with transvaginal ultrasound, and obtain serum samples to measure EE, LNG, estradiol (E2), and progesterone (P) levels. PK parameters were calculated and correlated with end-organ activity and compared against control samples obtained from normal and obese women sampled up to 48 h in a previous study. Standard determination of PK accuracy was performed; defined by the dependency on extrapolated values (‘excess’ area under the curve of 25% or less). Results The mean BMI was 39.4 kg/m2 (SD 6.6) with a range of 30–64 kg/m2. Key LNG PK parameters were as follows: clearance 0.52 L/h (SD 0.24), half-life 65 h (SD 40), AUC 232 h*ng/mL (SD 102) and time to reach steady-state 13.6 days (SD 8.4). The majority of subjects had increased ovarian activity with diameter of follicles ≥8 mm (n = 25) but only seven women had follicles ≥10 mm plus cervical mucus scores ≥5. Evidence of poor end-organ suppression did not correlate with the severity of the alterations in PK. As compared to historical normal and obese controls (48 h PK sampling), clearance, half-life, area under the curve (AUC) and time to reach steady-state were found to be significantly different (p ≤ 0.05) in obese women undergoing a longer duration of PK sampling (168 h). Longer sampling also improved PK accuracy for obese women (excess AUC 20%) as compared to both normal and obese controls undergoing shorter sampling times (48 h) with excess AUCs of 25% and 50%, respectively. Conclusions Obesity results in significant alterations in OC steroid PK parameters but the severity of these alterations did not correlate with end-organ suppression. A longer PK sampling interval (168 h vs. 48 h) improved the accuracy of PK testing.

SUMMARY The dopamine D2 receptors were investigated in vivo in eight neuroleptic-free patients with persistent tardive dyskinesia using positron emission tomography and 76Br-bromospiperone. The striatal receptor density, estimated by the striatum/cerebellum radioligand concentration ratio, was not elevated in patients as compared with age-matched controls but was positively correlated with the severity of orofacial dyskinesia assessed with the Abnormal Involuntary Movement Rating Scale. These results indicate that tardive dyskinesia is associated with normal levels of striatal D2 receptors but the severity of orofacial movements may depend on the relative density of striatal D2 receptors.Tardive dyskinesia (TD) is a protracted, sometimes permanent, complication of long-term neuroleptic treatment, affecting 13% to 31% of treated schizophrenic patients.'2 It is a distressing condition as the involuntary movements affect the orofacial musculature and often do not respond to therapy save for reintroduction or increased dosage of neuroleptics. There is no established preventive measure other than restricting prescription, and limiting both dosage and duration, of neuroleptic treatment as much as possible.3Brain dopamine receptor hypersensitivity is the most widely accepted hypothesis for the development of TD: it resembles levodopa-induced dyskinesia; it is both caused and controlled by dopaminergic antagonists and aggravated by dopaminergic agonists; during and following chronic neuroleptic treatment, rodents show increased behavioural responses to dopaminergic agonists with correlated increase in dopamine D2 receptor density in the striatum.4 Until now, however, no direct evidence for this role of striatal D2 receptors has been obtained in prospectively selected TD patients. We have evaluated striatal D2 receptors in TD patients in vivo using positron emission tomography (PET) and 76Br-bromospiperone to investigate the following hypothesis: (1) the striatal D2 receptors are increased in TD, and (2) the D2 receptor density is correlated to the severity of TD. Eight dyskinetic patients were studied after giving informed consent (table 1). The eight TD patients (7 women and I man, mean age 64-3 years, SD 4 7) were compared with eight agematched controls (3 women and 5 men, mean age 63 5, SD 2 6). The diagnosis of TD was established when abnormal involuntary movements (AIMS) (of a choreic nature), without other neurological abnormalities, had been permanent for the past 3 months, affecting in all cases the oro-linguofacial area and sometimes also the limbs or trunk, and had begun following a minimum of 3 months of exposure to neuroleptics, persisting at least 9 days after withdrawal of the neuroleptics (the type of which not being relevant). Neuroleptics had been prescribed, sometimes for many years, by general practitioners for reasons not always clear, particularly in the six chronically depressed patients. The characteristics ofdyskinesia and the plasma concentration of prolactin (as an index of neuroleptic medicati...

Objective Pharmacokinetics of norethindrone in combination oral contraceptive regimen are well described among HIV+ women treated with ritonavir boosted protease inhibitor therapies; however such characterization is lacking in women using progestin-only contraception. Our objective is to characterize pharmacokinetics of norethindrone in HIV+ women using ritonavir boosted atazanavir treatment during progestin-only contraceptive regimens. Study Design An open-label, prospective, non-randomized trial to characterize the pharmacokinetics of norethindrone in HIV+ women receiving ritonavir boosted atazanavir (n=10;treatment group) and other antiretroviral therapy known to not alter norethindrone levels (n=17;control group) was conducted. Following informed consent, women were instructed to take a single daily fixed oral dose of 0.35 mg norethindrone and 300mg/100mg atazanavir/ritonavir for 22 days. On day 22 serial blood samples were collected by venous catheter at 0, 1, 2, 3, 4, 6, 8, 12, 24, 48, and 72 hours. Whole blood was processed to collect serum and stored at −20°C until later analysis using radioimmunoassay. Pharmacokinetic parameters were estimated using non-compartmental method. Results In the treatment group, compared to the control group, an increase in area under the curve0-24 (16.69hr*ng/mL vs. 25.20hr*ng/mL; p<0.05) and maximum serum concentration (2.09ng/mL vs. 3.19ng/mL; p<0.05), decrease (25-40%) in apparent volume of distribution and apparent clearance, and unaltered half-life were observed. Conclusion(s) Our findings suggest that progestin-only contraceptives, unlike combination oral contraceptives, benefit from drug-drug interaction and achieve higher levels of exposure. Further studies are needed to establish whether pharmacokinetic interaction leads to favorable clinical outcomes.

Perinatal growth restriction programs higher risk for chronic disease during adulthood via morphological and physiological changes in organ systems. Perinatal growth restriction is highly correlated with a decreased nephron number, altered renal function and subsequent hypertension. We hypothesize that such renal maladaptations result in altered pharmacologic patterns for life. Maternal protein restriction during gestation and lactation was used to induce perinatal growth restriction in the current study. The diuretic response of furosemide (2mg/kg single i.p dose) in perinatally growth restricted rats during adulthood was investigated. Diuresis, natriuresis and renal excretion of furosemide were significantly reduced relative to controls, indicative of decreased efficacy. While a modest 12% decrease in diuresis was observed in males, females experienced 26% reduction. It is important to note that the baseline urine output and natriuresis was similar between treatment groups. The in vitro renal and hepatic metabolism of furosemide, the in vivo urinary excretion of the metabolite, and the expression of renal drug transporters was unaltered. Creatinine clearance was significantly reduced by 15% and 19% in perinatally growth restricted male and female rats, respectively. Further evidence of renal insufficiency was suggested by decreased uric acid clearance. Renal protein expression of sodium-potassium-chloride cotransporter, a pharmacodynamic target, was unaltered. In summary, perinatal growth restriction could permanently imprint pharmacokinetic processes affecting drug response.

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Formation of dextrorphan (DXT) from dextromethorphan (DXM) has been widely used to assess cytochrome P450 2D (CYP2D) activity. Additionally, the kinetics of CYP2D activity have been well characterized in the liver microsomes. However, studies in brain microsomes are limited due to the lower microsomal content and abundance of CYP2D in the brain relative to the liver. In the present study, we developed a micro-scale enzymatic incubation method, coupled with a sensitive UPLC-MS/MS assay for the quantitation of the rate of DXT formation from DXM in brain microsomes. Rat brain microsomes were incubated with different concentrations of DXM for various times. The reaction was stopped, and the proteins were precipitated by the addition of acetonitrile, containing internal standard (d-DXT). After centrifugation, supernatant (2 μL) was injected onto a UPLC, C18 column with gradient elution. Analytes were quantitated using triple-quadrupole MS/MS with electrospray ionization in positive ion mode. The assay, which was validated for accuracy and precision in the linear range of 0.25 nM to 100 nM DXT, has a lower limit of quantitation of 0.125 fmol on the column. Using our optimized incubation and quantitation methods, we were able to reduce the incubation volume (25 μL), microsomal protein amount (5 μg), and incubation time (20 min), compared with reported methods. The method was successfully applied to estimation of the Michaelis-Menten (MM) kinetic parameters of dextromethorphan-O-demethylase activity in the rat brain microsomes (mean ± SD, n = 4), which showed a maximum velocity of 2.24 ± 0.42 pmol/min/mg and a MM constant of 282 ± 62 μM. It is concluded that by requiring far less biological material and time, our method represents a significant improvement over the existing techniques for investigation of CYP2D activity in rat brain microsomes.

Antagonism of glucagon’s biological action is a proven strategy for decreasing glucose in diabetic animals and patients. To achieve full, potent, and selective suppression, we chemically optimized N-terminally truncated glucagon fragments for the identification and establishment of the minimum sequence peptide, [Glu9]­glucagon(6–29) amide (11) as a full antagonist in cellular signaling and receptor binding (IC50 = 36 nM). Substitution of Phe6 with l-3-phenyllactic acid (Pla) produced [Pla6, Glu9]­glucagon(6–29) amide (21), resulting in a 3-fold improvement in receptor binding (IC50 = 12 nM) and enhanced antagonist potency. Further substitution of Glu9 and Asn28 with aspartic acid yielded [Pla6, Asp28]­glucagon amide (26), which demonstrated a further increase in inhibitory potency (IC50 = 9 nM), and improved aqueous solubility. Peptide 26 and a palmitoylated analogue, [Pla6, Lys10­(γGluγGlu-C16), Asp28]­glucagon(6–29) amide (31), displayed sustained duration in vivo action that successfully reversed glucagon-induced glucose elevation in mice.

Cytochrome P4501A1 (CYP1A1), an important drug metabolizing enzyme, is expressed in human placenta throughout gestation as well as in fetal liver. Obesity, a chronic inflammatory condition, is known to alter CYP enzyme expression in non-placental tissues. In the present study, we test the hypothesis that maternal obesity alters the distribution of CYP1A1 activity in feto-placental unit. Placentas were collected from non-obese (BMI<30) and obese (BMI>30) women at term. Livers were collected from gestation day 130 fetuses of non-human primates fed either control diet or high-fat diet (HFD). Cytosol and microsomes were collected using differential centrifugation, and incubated with 7-Ethoxyresorufin. The CYP1A1 specific activity (pmoles of resorufin formed/min/mg of protein) was measured at excitation/emission wavelength of 530/590nm. Placentas of obese women had significantly reduced microsomal CYP1A1 activity compared to non-obese women (0.046 vs. 0.082; p<0.05); however no such effect was observed on cytosolic activity. Similarly, fetal liver from HFD fed mothers had significantly reduced microsomal CYP1A1 activity (0.44±0.04 vs. 0.20±0.10; p<0.05), with no significant difference in cytosolic CYP1A1 activity (control, 1.23±0.20; HFD, 0.80±0.40). Interestingly, multiple linear regression analyses of placental efficiency indicates cytosolic CYP1A1 activity is a main effect (5.67±2.32 (β±SEM); p=0.022) along with BMI (−0.57±0.26; p=0.037), fetal gender (1.07±0.26; p<0.001), and maternal age (0.07±0.03; p=0.011). In summary, while maternal obesity affects microsomal CYP1A1 activity alone, cytosolic activity along with maternal BMI is an important determinant of placental efficiency. Together, these data suggest that maternal lifestyle could have a significant impact on CYP1A1 activity, and hints at a possible role for CYP1A1 in feto-placental growth and thereby well-being of fetus.