Effect of ß-cyclodextrin on intra and intermolecular Michael addition of some catechol derivatives.

The oxidation reactions of catechol, dopamine and epinephrine have been studied in the absence and presence of N-methylaniline by UV-Vis. Spectrophotometry. A variety of reaction pathways (inter and intramolecular reactions) that followed by this oxidation have been observed depending on the nature of catechol derivatives. The observed homogeneous rate constants of the reactions were estimated by fitting the absorption time profiles for each reaction. The effect of ß-cyclodextrin and its inclusion complex has also been studied on the chosen reactions. The formation constants of the complexes of catechol, dopamine and epinephrine with ß-cyclodextrin as well as the rate constants of the reactions of free and complexed forms have been obtained by fitting the absorption-time spectra to a proposed kinetic-equilibrium model.

Role of chitosan nanoparticles in the oral absorption of Gemcitabine.

Gemcitabine is a known cytotoxic agent with a wide spectrum of antitumor activity. It has been employed in therapeutic regimens for various malignancies such as the lung, ovary, breast, and bladder cancers. It also has been used in the treatment of pancreatic cancer, in combination chemotherapy of non-small cell lung cancer (NSCLC) and in leukemia. Its effect results from incorporation into DNA with subsequent inhibition of cell proliferation. Unfortunately, Gemcitabine is rapidly metabolized by the so-called cytidine-deaminase which limits its efficacy. Because of extensive deamination by intestinal cells, its oral administration results in very low bioavailability. The aim of this study was to introduce an oral formulation of the drug for the first time and improve its physicochemical properties. Chitosan nanoparticles containing were produced based on ionic gelation method and tripolyphosphate (TPP). Physicochemical properties such as particle size and shape, loading efficiency and release rate were evaluated. Oral absorption of both free and nanoparticle-loaded drugs was measured using the rat intestinal sac model. The Gemcitabine-loaded chitosan nanoparticles were spherical with a mean size of 95±8 nm and high drug loading (63%). The nanoparticles showed controlled release pattern characterized by a fast initial release (61%) during the first 8h, followed by slower and continuous release (74.66%). The absorption study showed that Gemcitabine intestinal transport increased 3-5 folds by loading in chitosan nanocarrier.

Assessment of osteoporosis in psoriasis with and without arthritis: correlation with disease severity.

BACKGROUND: The most frequent extracutaneous association with psoriasis is arthritis. Because proinflammatory cytokines are increased in psoriasis, patients with this disease may be more prone to osteoporosis than the healthy individuals. METHODS: We evaluated 50 patients with psoriasis, with or without psoriatic arthritis (PsA), for the presence and degree of osteoporosis by performing dual energy x-ray absorptiometry (DEXA) and obtaining serum osteoprotegrin (OPG) levels. In addition, we correlated these results with the extent of skin and joint disease. Psoriasis area and severity index (PASI) was determined in all 50 patients with psoriasis, and total joint score (TJS) was recorded in the 16 patients who also had PsA. Results of DEXA and serum OPG were also obtained for 20 healthy individuals who served as controls. RESULTS: Osteoprotegrin level was significantly increased in psoriasis patients (with or without PsA) vs. controls. However, DEXA revealed that PsA patients had a higher degree of osteoporosis in the femur neck and wrist. In PsA patients, TJS correlated positively with both disease duration and PASI but correlated negatively with Z score of the femur. CONCLUSION: Psoriasis patients with or without arthritis may suffer from osteoporosis as evidenced by significantly increased serum OPG. Prolonged and extensive cutaneous disease is an important risk factor for the development and severity of PsA. Patients with a greater number of affected joints are at higher risk of osteoporosis.