Unexpected Stability of a Prodrug to Enzymatic Hydrolysis within a Hydrated HPMC Matrix Tablet.

The uptake of alkaline phosphate present in dissolution medium into a hydrating hydroxypropyl methylcellulose matrix tablet and that its activity was retained therein was demonstrated. This presents a risk to the stability of prodrugs that are substrates of this enzyme such as phosphonooxymethyl derivative prodrugs. It was found that fostemsavir, a phosphonooxymethyl derivative prodrug being developed for the treatment of HIV-1 infection, was unexpectedly resistant to hydrolysis within a hydrated HPMC matrix when subjected to drug release testing in media containing alkaline phosphatase. Studies indicated that this was not due to microenvironmental pH effects, osmolality effects or effective phosphate concentration effects associated with the presence of the prodrug. That the prodrug and not its parent could affect enzyme activity in a concentration dependent manner, and that another phosphate ester prodrug fosphenytoin did not inhibit alkaline phosphatase activity within a hydrated HPMC matrix suggested that the unexpected stability of the HIV-1 therapy prodrug may be associated with the ability of the phosphate group-containing compound itself to inhibit the enzyme at the concentrations it exists at in the hydrated dosage form and so enables the development of the compound in this type of dosage form.

Imaging of the Effect of Alcohol-Containing Media on the Performance of Hypromellose Hydrophilic Matrix Tablets: Comparison of Direct Compression and Regular Grades of Polymer.

As the ingestion of drug products with alcohol could have adverse effects on the release of drugs from dosage forms, it is important to understand the mechanisms underpinning the influence on drug release by evaluating the effect of alcohol-containing media on the behaviour of pharmaceutical excipients. In this work, the effect of hydroalcoholic media containing up to 40% v/v absolute ethanol was evaluated, employing both the regular (CR) and direct compression grades (DC) of hypromellose. X-ray microtomography (XµT) and magnetic resonance imaging (MRI) were used as complementary techniques in determining the influence of the media composition on the ability of the CR and DC polymers to form and evolve the gel layer that controls drug release. Particle and powder properties of the polymer were characterised to determine any relationship to performance in hydroalcoholic media. Triboelectrification results showed the CR grade formulation to charge electropositively whereas the DC grade charged electronegatively. The flow properties also showed the DC grade to have a superior flow as compared to its CR counterpart. Differences in particle morphology between the grades influenced charging and flow behaviour of the powders; however, it did not seem to impact significantly either on the mechanical strength or the drug release properties of the compacted formulation using the model drug propranolol HCl. XµT and MRI imaging were successfully used as complementary techniques in determining the gel layer/hydration layer thickness measurements as the layer developed, as well as following ingress of hydroalcoholic media and its impact on the dry core. The result showed that although differences were present in the gel layer thickness potentially due to differences in particle morphology, this also did not impact significantly on the dissolution process, especially in acidic and hydroalcoholic media.

Dissolution testing of modified release products with biorelevant media: An OrBiTo ring study using the USP apparatus III and IV.

During the OrBiTo project, our knowledge on the gastrointestinal environment has improved substantially and biorelevant media composition have been refined. The aim of this study was to propose optimized biorelevant testing conditions for modified release products, to evaluate the reproducibility of the optimized compendial apparatus III (USP apparatus III) and compendial apparatus IV (USP apparatus IV, open-loop mode) dissolution methods and to evaluate the usefulness of these methods to forecast the direction of food effects, if any, based on the results of two «ring¼ studies and by using two model modified release (MR) products, Ciproxin / Cipro XR and COREG CR. Six OrBiTo partners participated in each of the ring studies. All laboratories were provided with standard protocols, pure drug substance, and dose units. For the USP apparatus III, the dissolution methods applied to Ciproxin / Cipro XR, a monolithic MR product of an active pharmaceutical ingredient (API) with moderate aqueous solubility, were robust with low intra- and inter-laboratory data variability. Data from all partners were in line on a qualitative basis with food effect data in humans. For the USP apparatus IV, the dissolution methods applied to COREG CR, a multiparticulate, pH dependent, MR product of an API with low and pH dependent solubility led to high intra- and inter- laboratory data variability. Data from all partners were in line, on a qualitative basis, with the previously observed food effects in humans.

Taking a break: The effect of taking a vacation from Facebook and Instagram on subjective well-being.

Social Networking Sites (SNS) such as Facebook and Instagram have relocated a large portion of people's social lives online, but can be intrusive and create social disturbances. Many people therefore consider taking an "SNS vacation." We investigated the effects of a one-week vacation from both Facebook and Instagram on subjective well-being, and whether this would vary for passive or active SNS users. Usage amount was measured objectively, using RescueTime software, to circumvent issues of self-report. Usage style was identified at pre-test, and SNS users with a more active or more passive usage style were assigned in equal numbers to the conditions of one-week SNS vacation (n = 40) or no SNS vacation (n = 38). Subjective well-being (life satisfaction, positive affect, and negative affect) was measured before and after the vacation period. At pre-test, more active SNS use was found to correlate positively with life satisfaction and positive affect, whereas more passive SNS use correlated positively with life satisfaction, but not positive affect. Surprisingly, at post-test the SNS vacation resulted in lower positive affect for active users and had no significant effects for passive users. This result is contrary to popular expectation, and indicates that SNS usage can be beneficial for active users. We suggest that SNS users should be educated in the benefits of an active usage style and that future research should consider the possibility of SNS addiction among more active users.

A novel co-processing method to manufacture an API for extended release formulation via formation of agglomerates of active ingredient and hydroxypropyl methylcellulose during crystallization.

A novel process for generating agglomerates of active pharmaceutical ingredient (API) and polymer by swelling the polymer in a water/organic mixture has been developed to address formulation issues resulting from a water sensitive, high drug load API with poor powder properties. Initially, the API is dissolved in water, following which hydroxypropyl methylcellulose (HPMC) is added, resulting in the imbibing of water, along with the dissolved API, into the HPMC matrix. The addition of acetone and isopropyl acetate (anti-solvents) then causes the API to crystallize inside and on the surface of HPMC agglomerates. The process was scaled up to 20 kg scale. The agglomerates of API and HPMC generated by this process are ∼350 µm diameter, robust, and have significantly better flow than the API as measured by Erweka flow testing. These agglomerates exhibit improved bulk density, acceptable chemical stability, and high compressibility. The agglomerates process well through roller compaction and tableting, with no flow or sticking issues. This process is potentially adaptable to other APIs with similar attributes.

Advances in mechanistic understanding of release rate control mechanisms of extended-release hydrophilic matrix tablets.

Approaches to characterizing and developing understanding around the mechanisms that control the release of drugs from hydrophilic matrix tablets are reviewed. While historical context is provided and direct physical characterization methods are described, recent advances including the role of percolation thresholds, the application on magnetic resonance and other spectroscopic imaging techniques are considered. The influence of polymer and dosage form characteristics are reviewed. The utility of mathematical modeling is described. Finally, how all the information derived from applying the developed mechanistic understanding from all of these tools can be brought together to develop a robust and reliable hydrophilic matrix extended-release tablet formulation is proposed.

Effect of hyperoxia on serine phosphorylation of apoptotic proteins in mitochondrial membranes of the cerebral cortex of newborn piglets.

Previous studies have shown that hyperoxia results in cerebral cortical neuronal apoptosis. Studies have also shown that phosphorylation of anti-apoptotic proteins Bcl-2 and Bcl-xl results in loss of their anti-apoptotic potential leading to alteration in mitochondrial membrane permeability and the release of apoptogenic proteins in the neuronal cell of the newborn piglets. The present study tests the hypothesis that cerebral hyperoxia will result in increased serine phosphorylation of apoptotic proteins Bcl-2, Bcl-xl, Bax, and Bad in the mitochondrial membranes of the cerebral cortex of newborn piglets. Twelve newborn piglets were divided into normoxic (Nx, n = 6) exposed to an FiO(2) of 0.21 for 1 h and hyperoxic (Hyx, n = 6) exposed to FiO(2) of 1.0 for 1 h. In the Hyx group, PaO(2) was maintained above 400 mmHg while the Nx group was kept at 80-100 mmHg. Cerebral cortical tissue was harvested and mitochondrial fractions were isolated. Mitochondrial membrane proteins were separated using 12% SDS-PAGE, and probed with anti-serine phosphorylated Bcl-2, Bcl-xl, Bax, and Bad antibodies. Protein bands were detected, analyzed by imaging densitometry and density expressed as absorbance (OD x mm(2)). Phosphorylated Bcl-2 (p-Bcl-2) protein density (OD x mm(2)) was 81.81 +/- 9.24 in Nx and 158.34 +/- 10.66 in Hyx (P < 0.05). Phosphorylated Bcl-xl (p-Bcl-xl) protein density was 52.98 +/- 3.59 in Nx and 99.62 +/- 18.22 in Hyx (P < 0.05). Phosphorylated Bax (p-Bax) protein was 161.13 +/- 6.27 in Nx and 174.21 +/- 15.95 in Hyx (P = NS). Phosphorylated Bad (p-Bad) protein was 166.24 +/- 9.47 in Nx 155.38 +/- 12.32 in Hyx (P = NS). The data show that there is a significant increase in serine phosphorylation of Bcl-2 and Bcl-xl proteins while phosphorylation of Bad and Bax proteins were not altered during hyperoxia in the mitochondrial fraction of the cerebral cortex of newborn piglets. We conclude that hyperoxia results in differential post-translational modification of anti-apoptotic proteins Bcl-2 and Bcl-xl as compared to pro-apoptotic proteins Bax and Bad in mitochondria. We speculate that phosphorylation of Bcl-2 and Bcl-xl will result in loss of their anti-apoptotic potential by preventing their dimerization with Bax leading to activation of the caspase cascade of neuronal death.