Co-administration of darunavir and a new pharmacokinetic booster: formulation strategies and evaluation in dogs.

Various formulations for combination of the anti-HIV protease inhibitor darunavir (DRV) and TMC41629, a pharmacokinetic booster for DRV, were studied. TMC41629 (a BCS-IV compound) was formulated in capsules, as polyethylene glycol 400 (PEG400) solution, binary or ternary self-microemulsifying drug delivery system (SMEDDS), inclusion complex with hydroxypropyl-beta-cyclodextrin (HPbetaCD) or polyvinylpyrrolidone-co-vinylacetate 64 (PVP/VA64) extrudate. In addition, tablets were prepared using unmilled or micronized powder and a disintegrant. On co-administration with DRV tablets in dogs, DRV plasma concentration levels were boosted by TMC41629, the PVP/VA64 extrudate achieving the highest DRV levels (2-fold increase). Yet, with extrudate prepared with both compounds, no boosting effect was observed, likely due to transition of DRV from crystalline solvate to amorphous state. Therefore, a co-formulation, combining DRV as crystalline solvate with amorphous TMC41629, was developed. DRV/kappa-carrageenan 80/20% (w/w) beads coated with TMC41629 released at least 80% within 1h in 0.01M HCl with 0.5% sodium lauryl sulphate, TMC41629 dissolving faster than DRV. In dogs, the DRV exposure increased 2.7-fold with the TMC41629-coated beads relative to DRV alone, yet remained lower, but less variable, than following co-administration as separate formulations. Coating of TMC41629 on DRV/kappa-carrageenan beads is a suitable technique for co-formulation, whereby TMC41629 can function as a booster of DRV.

Membrane rafts are involved in intracellular miconazole accumulation in yeast cells.

Azoles inhibit ergosterol biosynthesis, resulting in ergosterol depletion and accumulation of toxic 14alpha-methylated sterols in membranes of susceptible yeast. We demonstrated previously that miconazole induces actin cytoskeleton stabilization in Saccharomyces cerevisiae prior to induction of reactive oxygen species, pointing to an ancillary mode of action. Using a genome-wide agar-based screening, we demonstrate in this study that S. cerevisiae mutants affected in sphingolipid and ergosterol biosynthesis, namely ipt1, sur1, skn1, and erg3 deletion mutants, are miconazole-resistant, suggesting an involvement of membrane rafts in its mode of action. This is supported by the antagonizing effect of membrane raft-disturbing compounds on miconazole antifungal activity as well as on miconazole-induced actin cytoskeleton stabilization and reactive oxygen species accumulation. These antagonizing effects point to a primary role for membrane rafts in miconazole antifungal activity. We further show that this primary role of membrane rafts in miconazole action consists of mediating intracellular accumulation of miconazole in yeast cells.

Solid state characterization of the anti-HIV drug TMC114: interconversion of amorphous TMC114, TMC114 ethanolate and hydrate.

The interconversion of the ethanolate, hydrate and amorphous form of TMC114 ((3-[(4-amino-benzenesulfonyl)-isobutyl-amino]-1-benzyl-2-hydroxypropyl)-carbamic acid hexahydrofuro-[2,3-b]furan-3-yl ester) in open conditions was characterized. TMC114 hydrate and ethanolate form isostructural channel solvates. The crystal structure of TMC114 was obtained from single crystal X-ray diffraction, confirming that it is a channel solvate. Ethanol and water can exchange with one another. TMC114 ethanolate converts into TMC114 hydrate at moderate or high relative humidity (RH) at 25 degrees C, and it converts back into the ethanolate in ethanol atmosphere. The hydration level of the hydrate is determined by the environmental humidity. TMC114 hydrate collapses to the amorphous product when water is removed by drying at low RH or increasing temperature. TMC114 ethanolate becomes amorphous at elevated temperature in a dry environment below the desolvation temperature. Amorphous TMC114 obtained by dehydrating the hydrate during storage at room temperature/<5% RH, by increasing the temperature, or via desolvating the ethanolate by heating, converts into the hydrate at moderate or high RH at ambient conditions, and into TMC114 ethanolate in an ethanol atmosphere. Under ambient conditions, TMC114 ethanolate may convert into the hydrate, whereas the opposite will not occur under these conditions. The amorphous form, prepared by melting-quenching shows a limited water uptake. Whereas TMC114 ethanolate is stable in the commercialized drug product, special conditions can trigger its conversion.

Solid state characterization and crystal structure from X-ray powder diffraction of two polymorphic forms of ranitidine base.

Ranitidine hydrochloride (RAN-HCl), a known anti-ulcer drug, is the product of reaction between HCl and ranitidine base (RAN-B). RAN-HCl has been extensively studied; however this is not the case of the RAN-B. The solid state characterization of RAN-B polymorphs has been carried out using different analytical techniques (microscopy, thermal analysis, Fourier transform infrared spectrometry in the attenuated total reflection mode, (13)C-CPMAS-NMR spectroscopy and X-ray powder diffraction). The crystal structures of RAN-B form I and form II have been determined using conventional X-ray powder diffraction in combination with simulated annealing and whole profile pattern matching, and refined using rigid-body Rietveld refinement. RAN-B form I is a monoclinic polymorph with cell parameters: a = 7.317(2), b = 9.021(2), c = 25.098(6) A, beta = 95.690(1) degrees and space group P2(1)/c. The form II is orthorhombic: a = 31.252(4), b = 13.052(2), c = 8.0892(11) A with space group Pbca. In RAN-B polymorphs, the nitro group is involved in a strong intramolecular hydrogen bond responsible for the existence of a Z configuration in the enamine portion of the molecules. A tail to tail packing motif can be denoted via intermolecular hydrogen bonds. The crystal structures of RAN-B forms are compared to those of RAN-HCl polymorphs. RAN-B polymorphs are monotropic polymorphic pairs.

Powder for reconstitution of the anti-HIV-1 drug TMC278 - Formulation development, stability and animal studies.

Powders for reconstitution of the next-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) TMC278 with low water solubility were developed by using a spray-dry technology. Their flexible dosing ability makes them suitable for patients looking for a different approach for antiretroviral (ARV) therapy. The selection of formulation excipients was based on their potential to create and maintain supersaturation solubility of TMC278 in 0.01 M HCl. Suitable water-soluble carriers for TMC278 were selected by a supersaturation screening to formulate powders for reconstitution by spray-drying. The selected powders for reconstitution were compared to clinical tablets of TMC278.HCl, in vitro using dissolution and stability testing, and in vivo through administration to beagle dogs, fed immediately after dosing. The spray-dried powders for reconstitution made up of TMC278/PVP-VA 64 1:9 (w/w) and TMC278/PVP-VA 64/Cremophor EL 1:8.5:0.5 (w/w/w) showed ease of suspendability, nearly complete dissolution of the drug and acceptable stability after one month storage at 25 and 40 degrees C. In dogs, TMC278 was more slowly absorbed from tablets than from the suspended powders for reconstitution. Compared to the tablet, the relative bioavailability obtained with the powders ranged between 69% and 89% for TMC278/PVP-VA 64 1:9 (w/w) and between 85% and 157% for TMC278/PVP-VA 64/Cremophor EL 1:8.5:0.5 (w/w/w). The absence of differences in vivo and in vitro between the powders made an eventual choice very difficult, yet their advantageous in vivo behaviour and flexible dosing possibility may provide a starting point for paediatric formulations.

Development of an implantable infusion pump for sustained anti-HIV drug administration.

Factors such as insufficient drug potency, non-compliance and restricted tissue penetration contribute to incomplete suppression of Human Immunodeficiency Virus (HIV) and the difficulty to control this infection. Infusion via standard catheters can be a source of infection, which is potentially life threatening in these patients. We developed an implantable infusion pump, allowing to accommodate large volumes (16-50mL) of high viscous solutions (up to 23.96mPas at 39 degrees C) of anti-HIV agents and providing sustained release of medication: a standard Codman 3000 pump, which was initially developed to release aqueous solutions ( approximately 0.7mPas) into the spinal cord such as for pain medication, was transformed for release of viscous solutions up to 40mPas by adapting the diameter of the capillary flow restrictor, the capillary length and way of catheterisation--by placing the indwelling catheter in the vena cava. A pilot study of the pump implanted in 2 dogs showed continuous steady-state release of the protease inhibitor darunavir (25mg/dog/day administered for 25 days), thereby achieving plasma concentration levels of approximately 40ng/mL. Steady-state plasma levels were reproducible after monthly refill of the pumps. In conclusion, the implantable adapted Codman 3000 constant-flow infusion pump customized to anti-HIV therapy allows sustained release of anti-HIV medication and may represent an opportunity to reduce the pill burden and complexity of dosing schemes associated with common anti-HIV therapy.

Dog model with implanted pump to test boosters for antiretroviral medication.

A dog model was developed to test the capacity of boosters for antiretroviral medication. Two dogs were implanted with a modified constant-flow Codman 3000 infusion pump, adapted to release viscous solutions of darunavir (TMC114) at a constant rate of 25mg/dog/day in the venous blood stream. Booster candidates were given by oral gavage for at least 4 days up to maximum 7 days in cross-over fashion, separated by a wash-out period of minimum 1 week. The booster candidates were tested at doses of 20 and/or 40mg/kg/day: blood sampling for determination of the boosting effect was performed on the last day of booster administration. The model allowed to (1) compare the boosting ratio of these booster candidates based on the exposure (determination of the area under the curve (AUC) of darunavir in presence versus absence of the booster candidate), (2) detect delay in boosting activity by evaluation of the shift of Cmax of darunavir following booster administration versus the Cmax of the booster candidate) and (3) calculate the intrinsic booster capacity, by correcting for the systemic exposure of booster candidate by normalizing the booster ratio for the booster's AUC. The latter parameter (intrinsic booster capacity) allows to determine the booster's metabolic contribution in inhibiting the metabolism of antiretroviral medication (most likely via inhibition of CYP3A4), minimizing the impact of potential effects of the booster at the level of the gastro-intestinal tract.

Di-(2-ethylhexyl)phthalate and deep venous thrombosis in children: a clinical and experimental analysis.

BACKGROUND: Five children with catheter-related deep venous thrombosis were encountered in our PICU. Three types of polyvinyl chloride tubing for the administration of intravenous solutions were in use (Terumo, Codan, and Perfusend). All were di-(2-ethylhexyl)phthalate plasticized. We suspected problems with the Codan tubing. METHODS: Different types of tubing at different time intervals in vitro were investigated. Tubing segments were assessed on structural alterations by surface electron microscopy. High-performance liquid chromatography-diode array detection and liquid chromatography-mass spectrometry-diode array detection were performed to identify and to quantify di-(2-ethylhexyl)phthalate. The hospital's minimal clinical data set (coded with the International Classification of Diseases, Ninth Revision, Clinical Modification) was investigated on catheter-related deep venous thrombosis between 2000 and 2004. RESULTS: Surface electron microscopy demonstrated that the Codan tubing's inner surface was severely altered, showing large particles (34.5 +/- 6.1 microm). High-performance liquid chromatography documented that all Codan samples showed a peak at the di-(2-ethylhexyl)phthalate retention time. The analysis of the minimal clinical data set for total catheter-related deep venous thrombosis showed an unusual high incidence in 2001 (52) compared with the expected 36 per year. CONCLUSIONS: Such occurrence of catheter-related deep venous thrombosis led to the assumption that disintegration of intravenous tubing resulted in intravenous administration of debris. Our data suggested that the particles derived from the tubing are of such size that they might induce catheter-related deep venous thrombosis. The absence of catheter-related deep venous thrombosis caused by the introduction of submicron inline filters outlines the important pathophysiological role of di-(2-ethylhexyl)phthalate-plasticized particles in the onset of catheter-related deep venous thrombosis. Our data indicate that a considerable number of patients might have been exposed to di-(2-ethylhexyl)phthalate, and a major concern is whether this jeopardized the health of the patients at that time.