Revisiting FDA's 1995 Guidance on Bioequivalence Establishment of Topical Dermatologic Corticosteroids: New Research Based Recommendations.

Purpose: As per the US FDA guidance issued on June 2, 1995, the establishment of bioequivalence for topical dermatologic corticosteroids is based on comparing the pharmacodynamic (PD) effects of Test and Reference products at the dose duration corresponding to the population ED50, determined either by naïve pooled data or nonlinear mixed effect modeling (NLME). The guidance was introduced using a study case example where the expectation maximization (EM) NLME algorithm, as implemented in P-PHARM®, was used. Although EM methods are relatively common, other methods such as the First-Order Conditional Estimation (FOCE) as implemented in the NONMEM® software are even more common.

Effect of Food on the Pharmacokinetics of Single- and Multiple-Dose Hydrocodone Extended Release in Healthy Subjects.

Background And Objectives: Food intake can alter the pharmacokinetics of certain medications, including changes in their oral bioavailability, which is of particular concern for extended-release (ER) opioids because of the high drug loads. Two randomized, open-label studies assessed the effect of food on the pharmacokinetics of single and multiple doses of hydrocodone ER formulated with CIMA Abuse-Deterrence Technology.

Methods: Healthy subjects in fed and fasted states received single 90-mg doses of hydrocodone ER (Studies 1 and 2) or multiple doses of hydrocodone ER (45 mg twice daily on days 2-3, 60 mg twice daily on days 4-5, 90 mg twice daily on days 6-10, and 90 mg once in the morning on day 11) (Study 2).

A Review of the Pharmacokinetics of Levothyroxine for the Treatment of Hypothyroidism.

Thyroxine hormone has been recognised since the early part of the nineteenth century and levothyroxine has been available since the mid-nineteenth century as a replacement for deficient thyroid hormones. While levothyroxine remains the staple treatment for hypothyroidism even to this day, its optimal use can be challenging. As is often the case with older drugs, the pharmacokinetics of levothyroxine is often under-appreciated or misunderstood and many factors influence the optimal dosing of levothyroxine.

Performance of different population pharmacokinetic algorithms.

Background: There has been an increased focus on population pharmacokinetics (PK) to improve the drug development process since the "Critical Path paper" by the Food and Drug Administration. This increased interest has given rise to additional algorithms.

Objectives: The purpose of this exercise was to compare the new algorithms iterative-2-stage (ITS) and maximum likelihood expectation maximization (MLEM) available in ADAPT 5 with other methods.

How critical is the duration of the sampling scheme for the determination of half-life, characterization of exposure and assessment of bioequivalence?

In noncompartmental analysis, poor characterization of the terminal elimination rate constant (Kel) will lead to biased results for half-life and total exposure (AUCinf), providing incorrect relative bioavailability and bioequivalence conclusions. We set out to determine if the sampling scheme duration was crucial for proper half-life and AUCinf determination. Profiles for 1000 subjects were simulated with a sampling scheme covering five half-lives.

Pharmacokinetic equivalence of a levothyroxine sodium soft capsule manufactured using the new food and drug administration potency guidelines in healthy volunteers under fasting conditions.

Objective: To assess the pharmacokinetic equivalence of a new soft capsule formulation of levothyroxine versus a marketed reference product and to assess the soft capsule formulated with stricter potency guidelines versus the capsule before the implementation of the new potency rule.

Method: Two single-dose randomized two-way crossover pharmacokinetic equivalence studies and one dosage form proportionality single-dose study comparing low, medium, and high strengths of the new formulation. All three studies were performed in a clinical setting.

Effect of a single dose of ritonavir on the pharmacokinetic behavior of elvucitabine, a nucleoside reverse transcriptase inhibitor, administered in healthy volunteers.

The purpose of this study was to determine the effect of a single dose of 300 mg of ritonavir on the plasma pharmacokinetics (PK) of a single dose of 20 mg of elvucitabine when the two drugs were coadministered in healthy subjects. In a three-way crossover design, 30 subjects received 20 mg of elvucitabine, 300 mg of ritonavir, or 20 mg of elvucitabine coadministered with 300 mg of ritonavir. Elvucitabine concentrations were analyzed using a validated liquid chromatography-tandem mass spectrometry assay.

Multiple-dose pharmacokinetic behavior of elvucitabine, a nucleoside reverse transcriptase inhibitor, administered over 21 days with lopinavir-ritonavir in human immunodeficiency virus type 1-infected subjects.

The purpose of this study was to describe the plasma pharmacokinetics (PK) of elvucitabine at different doses when administered daily or every other day for 21 days with lopinavir-ritonavir (Kaletra) in human immunodeficiency virus (HIV)-infected subjects. Three different dosing regimens of elvucitabine were administered with lopinavir-ritonavir to 24 subjects with moderate levels of HIV. Plasma samples were collected over 35 days.

A Phase II study of intravenous exatecan mesylate (DX-8951f) administered daily for 5 days every 3 weeks to patients with metastatic breast carcinoma.

Background: The objective of the current study was to determine the antitumor activity, safety, and pharmacokinetic (PK) profile of exatecan mesylate in patients with anthracycline-resistant and taxane-resistant, metastatic breast carcinoma.

Methods: All patients had clinical evidence of metastatic breast carcinoma; disease resistance or progression after chemotherapy that included anthracyclines and taxanes; no prior chemotherapy with camptothecin derivatives; and bidimensionally measurable disease. The starting dose of exatecan mesylate was either 0.