A Phase 1 Trial to Evaluate the Relationship Between Fluoride Intake and Urinary Fluoride Excretion in Healthy Participants.

Chronic overexposure to fluoride can have deleterious effects in the musculoskeletal system. Some fluorine-containing therapeutics, such as voriconazole, release fluoride through metabolism. Therefore, drug-related fluoride exposure should be assessed for novel therapeutics suspected of releasing fluoride through metabolism. Two trials were conducted to identify the optimal method of assessing drug-related fluoride exposure. In trial 1, designed to assess reproducibility of fluoride pharmacokinetics in urine and plasma, 14 participants were administered a fluoride-restricted diet and once-daily doses of sodium fluoride (2.2 mg [1 mg of fluoride] on days 1 and 2; and 13.2 mg of sodium fluoride [6 mg of fluoride] on days 3 and 4). In trial 2, designed to confirm the selected method for fluoride detection, 12 participants were administered a fluoride-restricted diet and randomized to receive voriconazole (400 mg twice, 12 hours apart, on day 1 [131 mg/d of fluoride maximum], then 3 doses of 200 mg every 12 hours [65.3 mg/d of fluoride maximum]) or placebo. Plasma fluoride concentrations and urinary fluoride excretion were assessed in each trial. Assessment of plasma fluoride concentrations in trial 1 was limited by 301 of 854 samples (35.2%) below the lower limit of quantitation. Urine fluoride excretion was readily measured and demonstrated a decrease from baseline during the fluoride-restricted diet phase, as well as dose-proportional increases with fluoride administration. In trial 2, increases in urine fluoride were successfully observed in participants administered voriconazole. In conclusion, fluoride exposure was optimally assessed by urinary fluoride excretion in conjunction with strict dietary fluoride restrictions, as measurements were consistent and reproducible.

Fluoride Pharmacokinetics in Urine and Plasma Following Multiple Doses of MK-8507, an Investigational, Oral, Once-Weekly Nonnucleoside Reverse Transcriptase Inhibitor.

MK-8507 is an investigational HIV-1 nonnucleoside reverse transcriptase inhibitor being developed for the treatment of HIV-1 infection. MK-8507 contains 2 trifluoromethyl groups that may result in fluoride release through metabolism, but the extent of MK-8507-related fluoride release in humans has yet to be determined. This double-blind, placebo-controlled, 2-period, parallel-group, multiple-dose trial in healthy participants without HIV-1 who were administered a fluoride-restricted diet and once-weekly doses of MK-8507 aimed to estimate the relationship between MK-8507 dose and fluoride exposure. A total of 15 adult male and 3 adult female (of non-childbearing potential) participants were randomized to receive MK-8507 200 mg (n = 6), MK-8507 800 mg (n = 6), or placebo (n = 6). Change from baseline in mean daily fluoride excretion averaged over 7 days following the administration of MK-8507 200 mg resulted in a net mean increase of 19.8 µmol (90% confidence interval, 12.2-27.4) relative to placebo and did not exceed 57 µmol, a threshold related to the mean difference between the daily reference dose set by the US Environmental Protection Agency and the average dietary fluoride intake in the United States. However, daily urinary fluoride excretion exceeded the threshold following administration of 800 mg MK-8507 (75.1 µmol [90% confidence interval, 67.5-82.7]). Assuming a linear relationship between MK-8507 dose and estimated mean daily fluoride released at steady-state, data interpolation suggests that the US Environmental Protection Agency reference dose for fluoride would not be exceeded in most patients when administering MK-8507 at doses currently under clinical investigation (≤400 mg once weekly).

A Microdose Cocktail to Evaluate Drug Interactions in Patients with Renal Impairment.

Renal impairment (RI) is known to influence the pharmacokinetics of nonrenally eliminated drugs, although the mechanism and clinical impact is poorly understood. We assessed the impact of RI and single dose oral rifampin (RIF) on the pharmacokinetics of CYP3A, OATP1B, P-gp, and BCRP substrates using a microdose cocktail and OATP1B endogenous biomarkers. RI alone had no impact on midazolam (MDZ), maximum plasma concentration (Cmax ), and area under the curve (AUC), but a progressive increase in AUC with RI severity for dabigatran (DABI), and up to ~2-fold higher AUC for pitavastatin (PTV), rosuvastatin (RSV), and atorvastatin (ATV) for all degrees of RI was observed. RIF did not impact MDZ, had a progressively smaller DABI drug-drug interaction (DDI) with increasing RI severity, a similar 3.1-fold to 4.4-fold increase in PTV and RSV AUC in healthy volunteers and patients with RI, and a diminishing DDI with RI severity from 6.1-fold to 4.7-fold for ATV. Endogenous biomarkers of OATP1B (bilirubin, coproporphyrin I/III, and sulfated bile salts) were generally not impacted by RI, and RIF effects on these biomarkers in RI were comparable or larger than those in healthy volunteers. The lack of a trend with RI severity of PTV and several OATP1B biomarkers, suggests that mechanisms beyond RI directly impacting OATP1B activity could also be considered. The DABI, RSV, and ATV data suggest an impact of RI on intestinal P-gp, and potentially BCRP activity. Therefore, DDI data from healthy volunteers may represent a worst-case scenario for clinically derisking P-gp and BCRP substrates in the setting of RI.

Anchored Aluminum Catalyzed Meerwein-Ponndorf-Verley Reduction at the Metal Nodes of Robust MOFs.

Catalytic Meerwein-Ponndorf-Verley reductions of ketones and aldehydes in the presence of isopropyl alcohol were performed at aluminum alkoxide sites that were postsynthetically introduced into robust metal-organic frameworks (MOFs). The aluminum was anchored at the bridging hydroxyl sites inherent in some MOFs. MOFs in the UiO-66/67 family as well as DUT-5 were successfully adapted to this strategy. Incorporation of catalytically active aluminum species greatly enhanced the reactivity of the native MOF at 80 °C in the case of both UiO-66, and was almost solely responsible for catalytic activity in the case of metalated UiO-66 and DUT-5. The site isolation of the catalyst prevented aggregation and complete deactivation of the molecular aluminum catalyst, allowing it to be recovered and recycled in the case of UiO-67. This catalyst also proved to be moderately tolerant to wet isopropyl alcohol.

Single- and Multiple-Dose Pharmacokinetics of Once-Daily Formulations of Raltegravir.

A new once-daily formulation of raltegravir, an integrase strand transfer inhibitor indicated in combination with other antiretroviral drugs for the treatment of human immunodeficiency virus-1 infection, is under development. Single-dose and steady-state pharmacokinetics of 1200 mg for 2 formulations of raltegravir were characterized in 2 open-label phase 1 studies in healthy male and female subjects aged 18 to 55 years. The new raltegravir 600-mg formulation had a higher relative bioavailability compared with the 400-mg tablets. Once absorbed, both 3 × 400-mg and 2 × 600-mg dosage forms of raltegravir exhibited similar systemic pharmacokinetics; in dictating bioavailability, differences were from increased absorption that was the result of improved in vivo disintegration/dissolution. Food had a smaller effect on the pharmacokinetics of raltegravir when given as 2 × 600-mg formulation (42% vs 73% decrease in AUC0-last ). Steady state was generally reached in 2 days, with little to no accumulation with multiple-dose administration. Raltegravir 1200 mg was found to exhibit pharmacokinetic properties amenable for once-daily dosing and was generally well tolerated in healthy subjects after single and multiple doses. The new formulation improved the bioavailability of this Biopharmaceutics Classification System class II compound.

On the Use of Group Sequential Study Designs for the Test of Bioequivalence for Complicated Products.

A novel modeling approach together with a use of group sequential study design for a complicated triple fixed-dose combination was attempted. Probability of success (POS) was used for determining a weighted average power, where weight was based on available information such as data from previous pilot studies or literature. A simulation study was conducted that resulted in the development of the necessary sample size for the studies in addition to identifying a decision algorithm that was prospectively defined in the protocols. Prospective inclusion of decision algorithms in the respective protocols facilitated a decision analytic approach to continuance or discontinuance of the product concept. Whereas the data suggested going to stage 2 was appropriate, the overall POS of meeting the equivalence requirements upon completion of the study were very low, leading to termination of the selected formulation concepts. The use of such novel designs for bioequivalence assessment can be applied for staged investments, particularly when there is uncertainty in formulation POS or when the pilot-scale pharmacokinetic studies are not likely to predict the final-scale pivotal studies.

Topical safety and vasoconstrictive assay-based bioequivalence of a new reformulated mometasone cream.

OBJECTIVES: A new improved mometasone furoate (Elocon™) cream with an emulsification system that produces a stable emulsion has been developed. In order to register the product in various markets, it was essential to ensure the cream was topically well tolerated and that it was bioequivalent to the reference product. METHODS: Phase I clinical studies were performed to assess the local safety and tolerability upon multiple dosing of this new cream as well as to assess the single-dose bioequivalence relative to the marketed product. Bioequivalence was assessed using a vasoconstrictive assay (VCA) after a dose-duration pilot study was completed with the marketed Elocon cream. KEY FINDINGS: The new mometasone cream and its vehicle were nonirritating in healthy subjects during 21-day patch application (MCII <0.025). The positive control was moderately irritating in the same study. The pivotal VCA study enrolled 162 subjects with 105 detectors included in the analysis of bioequivalence. In the 105 detectors, the ratio (×100%) of AUEC values at ED50 for test vs. standard (90% CI) was 112.91% (105.55, 120.87), within the bioequivalence criteria of (80, 125). CONCLUSIONS: These studies supported the registration of reformulated mometasone cream in various markets.

Efavirenz does not meaningfully affect the single dose pharmacokinetics of 1200 mg raltegravir.

Raltegravir is a human immunodeficiency virus (HIV)-1 integrase strand transfer inhibitor currently marketed at a dose of 400 mg twice daily (BID). Raltegravir for once daily regimen (QD) at a dose of 1200 mg (2 x 600 mg) is under development and offers a new treatment option for HIV-1 infected treatment-naive subjects. Since raltegravir is eliminated mainly by metabolism via an UDP-glucuronosyltransferase (UGT) 1 A1-mediated glucuronidation pathway, co-administration of UGT1A1 inducers may alter plasma levels of raltegravir. Efavirenz, an UGT1A1 inducer, was used to assess the impact of altered UGT activity on a 1200 mg QD dose of raltegravir. An open label, randomized, 2-period fixed-sequence Phase 1 study was performed in adult healthy male and female subjects (non-childbearing potential) ≥ 19 and ≤55 years of age, with a body mass index (BMI) ≥ 18.5 and ≤32.0 kg/m2 . Subjects (n = 21) received a single oral dose of 1200 mg raltegravir at bedtime on an empty stomach on Day 1 in Period 1. After a washout period of at least 7 days, subjects received oral doses of 600 mg efavirenz QD at bedtime for 14 consecutive days in Period 2. Subjects received a single oral dose of 1200 mg raltegravir co-administered with 600 mg efavirenz on Day 12 of Period 2. Pharmacokinetic (PK) samples were collected for 72 hours following raltegravir dosing and analyzed using a validated bioanalytical method to quantify raltegravir plasma concentrations. PK parameters were estimated using non-compartmental analysis. Administration of single 1200 mg oral doses of raltegravir alone and co-administered with multiple oral doses of efavirenz were generally well tolerated in healthy subjects. Co-administration with efavirenz yielded geometric mean ratios (GMRs) and their associated 90% confidence intervals (90% CIs) for raltegravir AUC0-∞, Cmax , and C24 of 0.86 (0.73, 1.01), 0.91 (0.70, 1.17), and 0.94 (0.76, 1.17), respectively. The results show that efavirenz modestly reduced the exposure of raltegravir. The reduction in raltegravir exposure is not considered clinically meaningful. Copyright © 2016 John Wiley & Sons, Ltd.

Atazanavir increases the plasma concentrations of 1200 mg raltegravir dose.

Raltegravir is a human immunodeficiency virus (HIV)-1 integrase strand transfer inhibitor currently marketed at a dose of 400 mg twice-daily (b.i.d.). Raltegravir 1200 mg once-daily (q.d.) (investigational q.d. formulation of 2 × 600 mg tablets; q.d. RAL) was found to be generally well tolerated and non-inferior to the marketed 400 mg b.i.d. dose at 48 weeks in a phase 3 trial. Since raltegravir is eliminated mainly by metabolism via a uridine diphosphate glucuronosyltransferase (UGT) 1A1-mediated glucuronidation pathway, co-administration of UGT1A1 inhibitors may increase the plasma levels of q.d. RAL. To assess this potential, the drug interaction of 1200 mg raltegravir using atazanavir, a known UGT1A1 inhibitor, was studied. An open-label, randomized, 2-period, fixed-sequence phase 1 study was performed in adult healthy male and female (non-childbearing potential) subjects ≥ 19 and ≤ 55 years of age, with a body mass index (BMI) ≥ 18.5 and ≤ 32.0 kg/m2 . Subjects (n = 14) received a single oral dose of 1200 mg raltegravir in period 1. After a washout period of at least 7 days, the subjects received oral doses of 400 mg atazanavir q.d. for 9 consecutive days, with a single oral dose of 1200 mg raltegravir co-administered on day 7 of period 2. Serial blood samples were collected for 72 h following raltegravir dosing and analysed using a validated bioanalytical method to quantify raltegravir plasma concentrations. Co-administration with atazanavir yielded GMRs (90% CIs) for raltegravir AUC0-∞ , Cmax and C24 of 1.67 (1.34, 2.10), 1.16 (1.01, 1.33) and 1.26 (1.08, 1.46), respectively. There was no effect of raltegravir on serum total bilirubin. In contrast, atazanavir increased the mean bilirubin by up to 200%, an effect that was preserved in the atazanavir/raltegravir treatment group. Administration of single q.d. RAL alone and co-administered with multiple oral doses of atazanavir were generally well tolerated in healthy subjects. The results show that atazanavir increased the PK exposure of raltegravir; therefore, co-administration of atazanavir with raltegravir q.d. is not recommended. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of metal-cation antacids on the pharmacokinetics of 1200 mg raltegravir.

OBJECTIVES: Raltegravir is a human immunodeficiency virus (HIV)-1 integrase strand transfer inhibitor currently marketed at a dose of 400 mg twice daily (BID). Raltegravir for once-daily regimen (QD) at a dose of 1200 mg is under development. The effect of calcium carbonate and magnesium/aluminium hydroxide antacids on the pharmacokinetics of a 1200 mg dose of raltegravir was assessed in this study. METHODS: An open-label, four-period, four-treatment, fixed-sequence study in 20 HIV-infected patients was performed. Patients needed to be on raltegravir as part of a stable treatment regimen for HIV, and upon entry into the trial received 5 days of 1200 mg raltegravir as pretreatment, before they entered the four-period study: 1200 mg of raltegravir alone (period 1), calcium carbonate antacid as TUMS® Ultra Strength (US) 1000 and 1200 mg raltegravir given concomitantly (Period 2), magnesium/aluminium hydroxide antacid as 20 ml MAALOX® Maximum Strength substitute MS given 12 h after administration of 1200 mg raltegravir (period 3), and calcium carbonate antacid as TUMS® US 1000 given 12 h after administration of 1200 mg raltegravir (period 4). Patients received their dose of 1200 mg QD raltegravir during the intervals between periods to re-establish steady state. AUC0-24 , C24 , Cmax and Tmax were calculated from the individual plasma concentrations of 1200 mg QD raltegravir after administration alone or with a calcium carbonate antacid or with a staggered dose of a calcium carbonate antacid or magnesium/aluminium hydroxide antacid. Adverse events, in addition to laboratory safety tests (haematology, serum chemistry and urinalysis), 12-lead electrocardiograms and vital signs were assessed. KEY FINDINGS: All treatments were well tolerated in the study. Metal-cation antacids variably affected the pharmacokinetics of 1200 mg QD raltegravir. When calcium carbonate antacid was given with 1200 mg raltegravir concomitantly, the geometric mean ratio (GMR) and its associated 90% confidence interval (90% CI) for AUC0-24 , Cmax and C24 h were 0.28 (0.24, 0.32), 0.26 (0.21, 0.32) and 0.52 (0.45, 0.61), respectively. When calcium carbonate antacid and magnesium/aluminium hydroxide were given 12 h after raltegravir 1200 mg QD dosing, the GMR (90% CI) values for AUC0-24 and Cmax were 0.90 (0.80, 1.03), 0.98 (0.81, 1.17), and 0.86 (0.73, 1.03), 0.86 (0.65, 1.15), respectively. However, significant reduction in the trough concentrations of raltegravir was observed: C24 h 0.43 (0.36, 0.51) in the presence of calcium carbonate antacids and 0.42 (0.34, 0.52) in presence of magnesium/aluminium hydroxide, respectively. CONCLUSIONS: Overall, the use of metal-cation antacids with 1200 mg QD raltegravir is not recommended.

Novel Gastroretentive Controlled Release Formulations for Once-Daily Administration: Assessment of Clinical Feasibility and Formulation Concept for Raltegravir.

BACKGROUND: Raltegravir is an integrase strand transfer inhibitor indicated in combination with other anti-retroviral medicinal products for the treatment of HIV-1 infection, given twice daily. Although a BCS class II compound, raltegravir exhibits low colonic absorption, thus making development of modified release formulations challenging. It was hypothesized that a gastroretentive (GR) formulation would increase trough (C24 h) concentrations of raltegravir, hence being amenable to a once-daily (QD) regimen. METHODS: Iterative prototype GR formulations were developed in monolithic, bilayer, and trilayer tablet designs. Four phase I studies in healthy subjects were conducted to provide proof of formulation concept. RESULTS: Raltegravir C24 h was increased by a GR formulation with scintigraphy data supporting gastric retention. Single-dose exposures from a trilayer tablet administered in the morning with a high-fat meal resulted in acceptable C24 h values. However, C24 h values for evening dosing with a high-fat meal did not meet the success criteria for QD administration. Raltegravir C24 h and area under the curve (AUC) values after AM dosing with a low-fat meal were significantly lower than after dosing with a moderate-fat meal. Skipping, delaying, or giving a low-fat, low-calorie lunch after dosing with a high-calorie breakfast also resulted in an unacceptable decline in C24 h values. The requirements for consistent product performance under varying conditions of diet, timing of dosing, and dose were not favorable when given as GR tablets. CONCLUSIONS: The findings from these studies offer valuable insights into modifying the absorption of candidate drugs with limiting colonic permeability and solubility characteristics and the interplay between meal, dose timing, and GR formulation performance.

Influence of renal and hepatic impairment on the pharmacokinetics of anacetrapib.

Two open-label, parallel-group studies evaluated the influence of renal and hepatic insufficiency on the pharmacokinetics of a single-dose anacetrapib 100 mg. Eligible participants included adult men and women with moderate hepatic impairment (assessed by Child-Pugh criteria) or severe renal impairment (CrCl <30 mL/min/1.73 m(2)). In both studies, patients were matched (race, age, sex, BMI) with healthy control subjects. Twenty-four subjects were randomized in each study (12 with either moderate hepatic or severe renal impairment and 12 matched healthy controls). In the hepatic insufficiency study, the geometric mean ratio (GMR; mean value for the group with moderate hepatic insufficiency/mean value for the healthy controls) and 90% CIs for the area under the concentration-time curve from time zero to infinity (AUC(0-∞)) and the maximum concentration of drug in plasma (C(max)) were 1.16 (0.84, 1.60) and 1.02 (0.71, 1.49), respectively. In the renal insufficiency study, the GMRs (mean value for the group with severe renal insufficiency/mean value for the healthy controls) and 90% CIs for AUC(0-∞) and Cmax were 1.14 (0.80, 1.63) and 1.31 (0.93, 1.83), respectively. Anacetrapib was generally well tolerated and there was no clinically meaningful effect of moderate hepatic or severe renal insufficiency on the pharmacokinetics of anacetrapib.

Single therapeutic and supratherapeutic doses of anacetrapib, a cholesteryl ester transfer protein inhibitor, do not prolong the QTcF interval in healthy volunteers.

Anacetrapib is a cholesteryl ester transfer protein inhibitor in Phase III development. This double-blind, double-dummy, randomized, placebo- and active-comparator-controlled, 4-period, balanced crossover study evaluated the effects of anacetrapib (100 mg and 800 mg) on QTcF interval in healthy subjects. QTcF measurements were made up to 24 h following administration of single doses of anacetrapib 100 or 800 mg, moxifloxacin 400 mg, or placebo in the fed state. The primary hypothesis was supported if the 90% CI for the least squares (LS) mean differences between anacetrapib 800 mg and placebo in QTcF interval change from baseline were entirely <10 msec at every post-dose time point (1, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 h). The upper bounds of the 90% CIs for LS mean differences from placebo in changes from baseline in QTcF intervals for anacetrapib 100 and 800 mg were <5 msec at every time point. In conclusion, single doses of anacetrapib 100 and 800 mg do not prolong the QTcF interval to a clinically meaningful degree relative to placebo and are generally well tolerated in healthy subjects.

A microwave powered injectable neural stimulator.

An unexpectedly simple implantable device that can achieve wireless neurostimulation consists of a short 1 cm long dipole platinum wire antenna, a Schottky diode, and a pulsed microwave transmitter. Fabricated into a 1 cm long by polyimide tubing, the implant can have a sub-millimeter diameter form factor suited to introduction into tissue by injection. Experiments that chronically implant the device next to a rat sciatic nerve show that a 915 MHz microwave transmitter emitting an average power of 0.5 watts has an ability to stimulate motor events when spaced up to 7 cm from the body surface. Tissue models consisting of saline filled tanks show the possibility of delivering milliampere pulsed current to neurosimulators though 5 centimeters or more of tissue. Such a neurostimulation system driven by microwave energy is limited in functional tissue depth by microwave SAR exposure. This report discusses some of the advantages and limitations of such a neurostimulation approach.

Bioavailability and short-term tolerability of alendronate in glucocorticoid-treated children.

BACKGROUND: Children receiving glucocorticoids (GCs) are at an increased risk of fragility fractures. Conservative measures may be inadequate in treating low bone mass, giving rise to fractures in this population; as such, attention has turned to the use of bisphosphonates. OBJECTIVE: The goal of this study was to evaluate the bioavailability and single-dose tolerability of alendronate (ALN) in children receiving a stable dose of GCs. METHODS: Children (ages 4-17 years) receiving GC treatment for their chronic illnesses received intravenous (125 µg) and oral (35 mg) ALN in a 2-period, randomized crossover study, with doses separated by at least a 7-day washout period. Urine was collected for either 8 or 24 hours after drug administration to determine urinary excretion of ALN and bioavailability. Tolerability was assessed by continuous collection of adverse events reported during the study. The main outcome measures were total urinary excretion rates, oral bioavailability of ALN, and adverse events. RESULTS: There were 12 patients in the 4- to 11-year-old group (mean age, 8.1 years; 5 girls) and 12 patients in the 12- to 17-year-old group (mean age, 14.3 years; 5 girls). The least-squares mean bioavailability (90% CI) for children aged 4 to 11 years (n = 12) was 0.43% (0.27-0.67) and for children aged 12 to 17 years (n = 12) it was 0.39% (0.26-0.60). The least-squares mean bioavailability for all ages combined was 0.41% (0.30-0.56), with no statistical difference between the 2 age groups. The total urinary excretion of ALN after the intravenous dose was similar between groups. Fifteen patients reported a total of 36 transient clinical nonserious adverse events, all of which were mild or moderate in intensity; the most common were headache (n = 13), abdominal pain (n = 3), limb, neck, or facial pain (n = 6), and ankle or knee swelling (n = 3). CONCLUSIONS: The mean oral bioavailability of ALN was similar to previous pharmacokinetic studies in children with osteogenesis imperfecta and slightly lower than that observed in historical adult controls. Alendronate was generally well tolerated, with minor adverse events that resolved uneventfully. Elucidation of the full adverse-effect profile of this agent was limited by the single-dose nature of this study, and robust comparisons of the pharmacokinetics of ALN in different age groups may need a larger number of patients.

Evaluation of pharmacokinetic parameters and dipeptidyl peptidase-4 inhibition following single doses of sitagliptin in healthy, young Japanese males.

AIMS: Sitagliptin is a selective inhibitor of dipeptidyl peptidase-4 (DPP-4) used to treat type 2 diabetes. The present aim was to evaluate pharmacokinetic (PK), pharmacodynamic (PD) and safety characteristics of sitagliptin following single doses in healthy, young Japanese males. METHODS: In this alternating two-panel, randomized, controlled double-blind study, six healthy Japanese male subjects (aged 20-46 years) in each panel received single oral doses of 5-400mg sitagliptin and two received placebo. Plasma and urine drug concentrations were measured from 0-48h post dose and plasma DPP-4 inhibition from 0-24h post dose. The results were compared with historical data from young, healthy non-Japanese males. RESULTS: Plasma concentrations of sitagliptin increased approximately in proportion to dose; maximum concentrations occurred 2-6h post-dose. The mean apparent terminal half-life for plasma sitagliptin was 9-14h, with the half-life slightly decreasing as the dose increased. The mean dose fraction excreted unchanged in the urine was 0.73-1.00. Ingestion of a traditional Japanese breakfast prior to dosing had only a minor effect on PK parameters. After correction for dilution and competition effects during assay, doses of sitagliptin ≥50mg resulted in weighted average DPP-4 inhibition from 0-24h post-dose >94% (without correction, >78%). No clinically meaningful differences in PK and DPP-4 inhibition parameters were found between Japanese and non-Japanese subjects. Sitagliptin was generally well tolerated and there were no serious adverse experiences or episodes of hypoglycaemia. CONCLUSIONS: The PK and PD findings from this study are consistent with once daily dosing of sitagliptin in Japanese patients with type 2 diabetes.

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, does not affect the pharmacokinetics of ethinyl estradiol or norethindrone in healthy female subjects.

Sitagliptin is a dipeptidyl peptidase-IV (DPP-4) inhibitor used for the treatment of patients with type 2 diabetes mellitus. This randomized, placebo-controlled, 2-period, crossover study evaluated the effect of sitagliptin on the pharmacokinetics of 17 α-ethinyl estradiol (EE(2)) and norethindrone (NET) in healthy female subjects who were receiving oral contraceptives for >3 months prior to enrollment. A total of 18 subjects with normal menstrual cycles received the oral contraceptive pill ORTHO-NOVUM(®) 7/7/7 on days 1 to 28 for 2 successive cycles, and on days 1 to 21 were randomly assigned to receive sitagliptin 200 mg/day (2 × 100 mg tablets) or placebo using a computer-generated allocation schedule. Blood samples for determination of plasma EE(2) and NET concentrations were collected predose and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 18, and 24 hours postdose on day 20 or 21 of each treatment period. The GMRs (90% confidence interval [CI]) for the AUC(0-24 hr) of EE(2) and NET were 0.99 (0.93, 1.06) and 1.03 (0.97, 1.09), respectively, and for C(max) were 0.97 (0.86, 1.10) and 0.98 (0.89, 1.07), respectively. The coadministration of sitagliptin 200 mg/day with an oral contraceptive for 21 days did not lead to clinically meaningful alterations in the pharmacokinetics of EE(2) and NET.

Effect of different durations and formulations of diltiazem on the single-dose pharmacokinetics of midazolam: how long do we go?

Understanding how inhibition of cytochrome P4503A (CYP3A) affects the metabolism of a new drug is critical in determining if a clinically relevant drug interaction will occur. Diltiazem interaction studies assess a given compound's sensitivity to moderate CYP3A inhibition. The present study compared the effect different durations and formulations of diltiazem (extended release [XR] and conventional release [CR]) had on the single-dose pharmacokinetics of midazolam. The geometric mean ratio (GMR; midazolam + diltiazem(XR × 5 days)/midazolam + diltiazem(XR × 2 days)) for midazolam AUC(0-∞) was 0.98 (90% confidence interval [CI], 0.87, 1.10). The GMR (midazolam + diltiazem(XR × 2 days)/midazolam + diltiazem(CR × 2 days)) for midazolam AUC(0-∞) was 0.82 (90% CI, 0.73, 0.92). Simcyp simulations accurately predicted the observed clinical results only when a hepatic CYP3A degradation rate (k(deg)) different from that provided by the software was used. The data suggest that dosing diltiazem XR for 2 days predicts the change in midazolam AUC as reliably as 5 days of XR dosing and 2 days of CR dosing. In addition, the authors believe that a hepatic CYP3A kdeg of 0.03 h(-1) should be considered for future Simcyp studies.

Bioavailability of alendronate and vitamin D(3) in an alendronate/vitamin D(3) combination tablet.

These studies were designed to demonstrate that the alendronate (ALN) component of an ALN/vitamin D(3) combination tablet was bioequivalent to the 70-mg ALN tablet and that the pharmacokinetic parameters of vitamin D(3) were similar with or without ALN. These were open-label, randomized, 2-part, 2-period, crossover studies. In part I, participants received either a single combination tablet or ALN 70 mg. In part II, participants received either a single combination tablet or vitamin D(3) alone. Results from part I showed that the geometric mean ratio (GMR) for total urinary excretion of ALN for both studies fell within the prespecified bioequivalence bounds. Results from part II showed that the pharmacokinetic profiles of vitamin D(3) with or without ALN were also similar. The combination tablets are bioequivalent to the ALN 70-mg tablet with respect to ALN bioavailability. The bioavailability of vitamin D(3) is similar in the combination tablets and when administered alone. No serious adverse experiences were reported.

Wireless ultrasound-powered biotelemetry for implants.

A miniature piezoelectric receiver coupled to a diode is evaluated as a simple device for wireless transmission of bioelectric events to the body surface. The device converts the energy of a surface-applied ultrasound beam to a high frequency carrier current in solution. Bioelectrical currents near the implant modulate the carrier amplitude, and this signal is remotely detected and demodulated to recover the biopotential waveform. This technique achieves millivolt sensitivity in saline tank tests, and further attention to system design is expected to improve sensitivity.