Understanding impact of pre-dissolved polymers on dissolution behavior of soluble carbamazepine cocrystal.

Cocrystallization is a novel approach for tackling the lower solubility concerns when they can yield solution concentration a lot better than their corresponding parent drug in crystalline form. To get the actual solubility and dissolution gains offered by the cocrystals, phase changes in solution (dissolution) has to be interrupted. In current study, we selected commonly used polymers in order to study their effects on the super saturation of carbamezepine-succinic acid (CBZ-SUC) cocrystal during dissolution studies. To observe solid phase changes during dissolution in situ Raman spectroscopy was used. At the completion of each test the solid phase was analyzed by Fourier-transform infrared spectroscopy (FTIR) and powder X-Ray diffractometry. In polymers absence, no dissolution improvement was achieved by the cocrystal owing to its quick transformation to the stable carbamazepine dihydrate (CBZDH). Pre-dissolved PVP at 2% w/v concentration did not inhibit CBZ crystallization as a dihydrate, whereas at 0.025% w/v pre-dissolved hydroxypropyl methyl cellulose acetate succinate (HPMCAS) did stabilize the cocrystal in buffer solution (pH 6.8) for the course of time studied. This cocrystal stabilization resulted in enhanced CBZ solubility ( Ì´ 4fold) caused by cocrystal super saturation state. Seeding of this stable supersaturated state with 1% w/v CBZDH resulted in CBZ crystallization as dihydrate with ultimate loss of solubility advantage.

Pulmonary arterial enlargement and acute exacerbations of COPD.

BACKGROUND: Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with accelerated loss of lung function and death. Identification of patients at risk for these events, particularly those requiring hospitalization, is of major importance. Severe pulmonary hypertension is an important complication of advanced COPD and predicts acute exacerbations, though pulmonary vascular abnormalities also occur early in the course of the disease. We hypothesized that a computed tomographic (CT) metric of pulmonary vascular disease (pulmonary artery enlargement, as determined by a ratio of the diameter of the pulmonary artery to the diameter of the aorta [PA:A ratio] of >1) would be associated with severe COPD exacerbations. METHODS: We conducted a multicenter, observational trial that enrolled current and former smokers with COPD. We determined the association between a PA:A ratio of more than 1 and a history at enrollment of severe exacerbations requiring hospitalization and then examined the usefulness of the ratio as a predictor of these events in a longitudinal follow-up of this cohort, as well as in an external validation cohort. We used logistic-regression and zero-inflated negative binomial regression analyses and adjusted for known risk factors for exacerbation. RESULTS: Multivariate logistic-regression analysis showed a significant association between a PA:A ratio of more than 1 and a history of severe exacerbations at the time of enrollment in the trial (odds ratio, 4.78; 95% confidence interval [CI], 3.43 to 6.65; P<0.001). A PA:A ratio of more than 1 was also independently associated with an increased risk of future severe exacerbations in both the trial cohort (odds ratio, 3.44; 95% CI, 2.78 to 4.25; P<0.001) and the external validation cohort (odds ratio, 2.80; 95% CI, 2.11 to 3.71; P<0.001). In both cohorts, among all the variables analyzed, a PA:A ratio of more than 1 had the strongest association with severe exacerbations. CONCLUSIONS: Pulmonary artery enlargement (a PA:A ratio of >1), as detected by CT, was associated with severe exacerbations of COPD. (Funded by the National Heart, Lung, and Blood Institute; ClinicalTrials.gov numbers, NCT00608764 and NCT00292552.).