Mathematical modeling of drug release profiles for modified hydrophobic HPMC based gels.

Hydroxypropyl methylcellulose (HPMC) is now available in modified hydrophobic forms (Sangelose). In this paper, the effect of viscosity grade and HPMC concentration on in vitro release kinetics of a topically applied drug were studied using gel formulations of a nonsteroidal anti-inflammatory drug (NSAID), diclofenac potassium (DP), with different viscosity grades of the polymer (60L, 60 M, 90 M for hydrophobic HPMC and 50 cPs for conventional hydrophilic HPMC) in different proportions. It was found that hydrophobic HPMC-based gels having a higher viscosity and lower polymer concentration release a notably higher amount of drug compared with hydrophilic HPMC-based gels containing a higher concentration of polymer but with lower viscosity. For gels, the suitability of different common empirical (zero-order, first-order, and Higuchi), and semi-empirical (Ritger-Peppas and Peppas-Sahlin) models, and some new statistical (logistic, log-logistic, Weibull, Gumbel, and generalized extreme value distribution) models to describe the drug release profile were tested through non-linear least-square curve fitting. A general purpose mathematical analysis tool MATLAB was used. Further, instead of the widely used transformed linear fit method, direct fitting was used in the paper to avoid any form of truncation and transformation errors. The results revealed that the log-logistic distribution, amongst all the models investigated, was the best fit for hydrophobic formulations. For hydrophilic ones, the semi-empirical models and Weibull distribution worked best, although log-logistic also showed a close fit. The shape parameter for the log-logistic and Weibull distribution conveys vital information about the rate of release and helps improve understanding of drug release profiles.

Screening for osteopenia and osteoporosis in an urban community in India.

Osteoporosis is a disease characterized by reduction in the bone mass and disruption of bone architecture leading to impaired skeletal strength and an increased susceptibility of fractures. It is a major public health problem associated with substantial morbidity and socio-economic burden worldwide. The present study was planned to screen bone status of adults over 20 years (when peak bone mass is formed) utilizing calcaneal quantitative ultrasound (QUS) (Hologic Sahara 0058 USG) as a diagnostic tool. A screening camp was conducted in the 1st week of February 2008 at the Terna Hospital and Research Centre along with the Orthopedic Department. A questionnaire was administered to all the screened individuals which included socio-demographic data, assessment of susceptibility to osteoporosis and dietary habits. The bone mineral density (BMD) was measured at the calcaneus by QUS and T-scores were calculated based on WHO criteria. The study yielded a prevalence of 41.4% among women and 33.33% among men for Osteopenia and 12.85% among women 3.7% among men for Osteoporosis respectively. The mean age of the screened sample was 44.25 years. The mean weight, height and body mass index was 56.95 kg, 157.47 cms and 23.047 respectively. The mean bone density was -0.749. A total of 97 individuals screened; of which 70 (72.1%) were females and 27 (27.9%) were males. There was a significant trend of decreasing bone density with an increase in age. Age had an influence on the outcome of osteopenic and osteoporosis score in present study. The subjects with low bone mineral density (BMD) were advised to undergo a Dual energy X-ray absorptiometry (DEXA) scan in order to confirm the diagnosis. The US Preventive Services Task Force recommends routine screening for Osteoporosis in women over 65 years. In India we need to carry out further studies on whether we need to consider screening at an earlier age and also to study osteoporosis in males.