Solubility and bioavailability improvement of pazopanib hydrochloride.

The anti-cancer drug pazopanib hydrochloride (PZH) has a very low aqueous solubility and a variable oral bioavailability. A new pharmaceutical formulation with an improved solubility may enhance the bioavailability and reduce the variability. A broad selection of polymer excipients was tested for their compatibility and solubilizing properties by conventional microscopic, thermal and spectrometric techniques. A wet milling and mixing technique was used to produce homogenous powder mixtures. The dissolution properties of the formulation were tested by a pH-switch dissolution model. The final formulation was tested in vivo in cancer patient following a dose escalation design. Of the tested mixture formulations, the one containing the co-block polymer Soluplus® in a 8:1 ratio with PZH performed best in terms of in vitro dissolution properties. The in vivo results indicated that 300 mg of the developed formulation yields similar exposure and a lower variability (379 µg/mL∗h (36.7% CV)) than previously reported values for the standard PZH formulation (Votrient®) at the approved dose of 800 mg. Furthermore, the expected plasma-Cthrough levels (27.2 µg/mL) exceeds the defined therapeutic efficacy threshold of 20 µg/mL.

Pharmacokinetics of Sustained-Release Oral Dexamphetamine Sulfate in Cocaine and Heroin-Dependent Patients.

INTRODUCTION: Research has shown that sustained-release (SR) dexamphetamine is a promising agonist treatment for cocaine dependence. However, little is known about the pharmacokinetics (PKs) of SR oral dexamphetamine. This study examined the PKs of a new SR dexamphetamine formulation in cocaine plus heroin-dependent patients currently in heroin-assisted treatment. METHODS: The study was designed as an open-label PK study in 2 cohorts: n = 5 with once daily 60 mg and n = 7 with once daily 30 mg SR oral dexamphetamine. Five days of blood plasma dexamphetamine concentrations measured with liquid chromatography-mass spectrometry with PK parameter estimates using noncompartmental analysis. RESULTS: Twelve cocaine-dependent plus heroin-dependent patients in heroin-assisted treatment were included. The initial cohort 1 dose of 60 mg once daily was adjusted to 30 mg after mild to moderate adverse events. After oral administration, tmax values (coefficient of variation %) were 6.0 (17.0%) and 6.3 (16.3%) hours and t1/2 were 11 (24.6%) and 12 (25.4%) hours for 60 mg and 30 mg SR dexamphetamine, respectively. At steady state, CSSmax values were reached at 100 (27.5%) ng/mL and 58.4 (14.4%) ng/mL, whereas CSSmin values were 39.5 (38.9%) ng/mL and 21.8 (19.8%) ng/mL for 60 mg and 30 mg, respectively. CONCLUSIONS: The investigated SR formulation of dexamphetamine showed favorable slow-release characteristics in cocaine and heroin-dependent patients. A dose-proportional steady-state concentration was achieved within 3 days. These findings support the suitability of the SR formulation in the treatment of cocaine dependence.

Thermal stability study of crystalline and novel spray-dried amorphous nilotinib hydrochloride.

The thermal characteristics and the thermal degradation of crystalline and amorphous nilotinib hydrochloride (NH) were studied. The spray drying technique was successfully utilized for the amorphization of NH and was evaluated by spectroscopic techniques and differential scanning calorimetry (DSC). The ethanolic spray drying process yielded amorphous NH with a glass transition temperature (Tg) of 147°C. Thermal characterization of the amorphous phase was performed by heat capacity measurements using modulated DSC (mDSC). Thermal degradation was studied by thermogravimetric analysis (TGA). The derived thermodynamic properties of the amorphous NH indicate fragile behaviour and a low crystallization tendency. NH was found to be molecularly stable up to 193°C. After which, the thermal degradation displayed two phases. The values of the thermal degradation parameters were estimated using the Ozawa-Flynn-Wall and Friedman non-isothermal, model-free, isoconversional methods The results indicate the two phases to be single-step reactions. The examination of the physical stability of amorphous NH during storage and at elevated temperatures showed stability at 180°C for at least 5h and at 20-25°C/60% RH for at least 6 months. During these periods, no crystallization was observed. This study is the first to report the thermal characteristics of NH. Additionally, it is also the first to describe the full thermal analysis of a spray-dried amorphous drug. The thermal data may be used in the projection of future production processes and storage conditions of amorphous NH.

Improving the solubility of nilotinib through novel spray-dried solid dispersions.

The tyrosine kinase inhibitor nilotinib has a very low aqueous solubility and a low and variable oral bioavailability. A pharmaceutical formulation with an improved solubility may enhance the bioavailability and reduce the variability thereof and of the pharmacokinetics. The aim of this study was to enhance the solubility of nilotinib by developing a spray dried solid dispersion. A broad selection of polymer excipients were tested for solubilizing properties. The spray drying technique was used to produce solid dispersions of nilotinib hydrochloride (NH) in matrices of the best performing polymers. Both the dissolution and physicochemical characteristics of the formulations were studied using a pH-switch dissolution model and conventional microscopic, thermal and spectrometric techniques. Of the tested spray dried solid dispersions, the ones containing the co-block polymer Soluplus® performed best in terms of in vitro dissolution properties. Further testing led to an optimized weight ratio of 1:7 (NH:Soluplus®) that improved the solubility up to 630-fold compared to crystalline NH (1.5µg/mL) in simulated intestinal fluid. This effect can be attributed to the amorphization of NH and the solubilization of the drug due to micelle formation. A spray dried solid dispersion formulation of NH with Soluplus® in a ratio of 1:7 was developed that showed a significant increase in solubility.

High-Tech Drugs in Creaky Formulations.

Recent literature reviews and registration documents covering novel Signal Transduction Inhibitors in the treatment of cancer paint a picture of inefficiency and variability, where formulation improvements could be valuable. In this article, we discuss apparent drug design flaws as we impose the current standard formulation practice.

Quantification of 11 Therapeutic Kinase Inhibitors in Human Plasma for Therapeutic Drug Monitoring Using Liquid Chromatography Coupled With Tandem Mass Spectrometry.

BACKGROUND: A liquid chromatography/tandem mass spectrometry assay was developed to facilitate therapeutic drug monitoring (TDM) for 10 anticancer compounds (dasatinib, erlotinib, gefitinib, imatinib, lapatinib, nilotinib, pazopanib, sorafenib, sunitinib, and vemurafenib) and the active metabolite, N-desethyl-sunitinib. METHODS: The TDM assay is based on reversed-phase chromatography coupled with tandem mass spectrometry in the positive ion mode using multiple reaction monitoring for analyte quantification. Stable isotopically labeled compounds were used as internal standards. The sample pretreatment consisted of protein precipitation with acetonitrile using a small plasma volume of 50 µL. The validation procedures were based on the guidelines on bioanalytical methods issued by the US Food and Drug Administration and were modified to fit the requirements of the clinical TDM environment. RESULTS: The method was validated over a linear range of 5.00-100 ng/mL for dasatinib, sunitinib, and N-desethyl-sunitinib; 50.0-1000 ng/mL for gefitinib and lapatinib; 125-2500 ng/mL for erlotinib, imatinib, and nilotinib; and 500-10,000 ng/mL for pazopanib, sorafenib, and vemurafenib. The results of the validation study demonstrated good intra-assay and interassay accuracy (bias <6.0%) and precision (12.2%) for all analytes. CONCLUSIONS: This newly validated method met the criteria for TDM and has successfully been applied to routine TDM service for tyrosine kinase inhibitors.

Variability in bioavailability of small molecular tyrosine kinase inhibitors.

Small molecular tyrosine kinase inhibitors (smTKIs) are in the centre of the very quickly expanding area of personalized chemotherapy and oral applicability thereof. The number of drugs in this class is rapidly growing, with twenty current approvals by both the European Medicines Agency (EMA) and the Food and Drug Administration (FDA). The drugs are, however, generally characterized by a poor oral, and thus variable, bioavailability. This results in significant variation in plasma levels and exposure. The cause is a complex interplay of factors, including poor aqueous solubility, issued permeability, membrane transport and enzymatic metabolism. Additionally, food and drug-drug interactions can play a significant role. The issues related with an impaired bioavailability generally receive little attention. To the best of our knowledge, this article is the first to provide an overview of the factors that determine the bioavailability of the smTKIs.