A headspace-gas chromatography method for isopropanol determination in warfarin sodium products as a measure of drug crystallinity.

Coumadin® a nd s everal generic products of warfarin s odium (WS) contain the crystalline form (clathrate) in which WS and isopropanol (IPA) are associated in a 2:1 molar ratio. IPA is critical in maintaining the WS crystalline structure. Physicochemical properties of the drug and drug product may change when the crystalline drug transforms to amorphous form.

Dose Uniformity of Scored and Unscored Tablets: Application of the FDA Tablet Scoring Guidance for Industry.

Purpose: This U.S. Food and Drug Administration (FDA) laboratory study examines the impact of tablet splitting, the effect of tablet splitters, and the presence of a tablet score on the dose uniformity of two model drugs.

Evaluation of In-Use Stability of Anticoagulant Drug Products: Warfarin Sodium.

The objective of the study was to evaluate the stability of warfarin products during use by patients or caregivers. For evaluation, three commercial products manufactured by different processes were selected and placed at 30°C/75%RH to simulate in use condition. Samples were withdrawn up to 12 weeks and analyzed for the physicochemical changes.

Stability of gabapentin 300-mg capsules repackaged in unit dose containers.

Purpose: The stability of a gabapentin 300-mg capsule product in the original bulk containers and repackaged in unit dose blister strips was studied.

Methods: Both products were stored for one year under long-term storage conditions (25 degrees C and 60% relative humidity [RH]) and for three months under accelerated storage conditions (40 degrees C and 75% RH) and tested for weight change, potency, and dissolution using validated analytical method.

Results: The capsules in the original containers showed no change in weight during the study period.

Development and application of a validated HPLC method for the analysis of dissolution samples of gabapentin drug products.

A simple isocratic reversed-phase HPLC method was developed and validated for the analysis of dissolution samples of gabapentin tablets and capsules. Separation of gabapentin from its major degradation impurity, 3,3-pentamethylene-4-butyrolactam was achieved on a Phenomenex Luna Cyano column using a methanol-acetonitrile-20 mM KH(2)PO(4) (pH 2.2) (5:5:90, v/v/v) mobile phase.

Comparison of the stability of split and intact gabapentin tablets.

The purpose of this study was to determine the stability differences between split and intact gabapentin tablets. Gabapentin tablets from three different manufacturers (G1, G2 and G3) were tested for a period of 9 weeks under long-term (25 degrees C/60% RH) and intermediate stability (30 degrees C/60% RH) storage conditions after storage in closed amber pharmacy dispensing containers. Samples were analyzed for dissolution and potency using validated HPLC methods.

Development and application of a validated HPLC method for the determination of gabapentin and its major degradation impurity in drug products.

A simple isocratic reversed-phase HPLC method for the determination of gabapentin and its major degradation impurity, 3,3-pentamethylene-4-butyrolactam, was developed and validated for use in the analysis of pharmaceutical tablets and capsules. Separation was achieved on a Brownlee Spheri-5 Cyano column using an acetonitrile-10 mM KH2PO4/10 mM K2HPO4 (pH 6.2) (8:92, v/v) mobile phase.

The effect of food on the relative bioavailability of rapidly dissolving immediate-release solid oral products containing highly soluble drugs.

The purpose of this study is to test the hypothesis that rapidly dissolving immediate-release (IR) solid oral products containing a highly soluble and highly permeable drug [biopharmaceutical classification system (BCS) class I] are bioequivalent under fed conditions. Metoprolol and propranolol (BCS class I) as well as hydrochlorothiazide (BCS class III) were selected as model drugs. The relative bioavailability of two FDA approved (Orange Book AB rating) solid oral dosage forms of metoprolol and propranolol/hydrochlorothiazide (combination tablets) was evaluated in human volunteers under fed conditions using a two-way crossover design.

Determination of plasma and brain levels of isotretinoin in mice following single oral dose by high-performance liquid chromatography.

An isocratic reversed-phase high-performance liquid chromatographic method was established and validated according to FDA's Guidance for Industry, "Bioanalytical Method Validation", for the determination of isotretinoin in plasma and brain tissue from mice following single and multiple oral doses of Accutane. Plasma sample preparation included deproteination with acetonitrile-perchloric acid followed by centrifugation. Brain tissue was homogenized and extracted with acetonitrile-perchloric acid followed by centrifugation.