Size exclusion chromatography: An effective tool for the estimation of Sirolimus levels.

Sirolimus, a lipophilic macrolide, is a well-known immunosuppressant drug used for coating coronary stents and for preventing rejection of kidney transplants in humans. Since Sirolimus is a relatively large molecule with an average mass 914.172 g/mol, size exclusion chromatography (SEC) was employed for exploring its potential for the estimation of Sirolimus content from blood samples. When human blood samples were spiked with known concentrations of Sirolimus, it was observed that it could be estimated with an average recovery of >90% and relative standard deviation <5%. Results indicated that Sirolimus could be estimated with impressive accuracy and repeatability by SEC technique.

Retention rate of Gabapentin in children with intractable epilepsies at 1 year.

Gabapentin (GAB) is a newer second-line antiepileptic drug (AED) used in children. This is a multi-centre retrospective observational study of the efficacy, tolerability and retention rate in 105 children, aged 0-17.5 years (mean 10.1) over a 14 year period. The median age of epilepsy onset was 2.5 years (range 0-14.6). 72% started GAB as at least the 3rd AED, with 43% having been withdrawn from at least 2 AEDs. 77% had focal and 52% symptomatic epilepsies. The maintenance doses for GAB ranged 6.0-87.3 mg/kg/day (mean 43.7). The study comprised 157 person-treatment years for GAB. GAB was well tolerated with 55% remaining on treatment beyond 1 year. No serious adverse events were reported whilst on GAB, but 39% reported possibly and probably related adverse events. Seizure improvement (<50% seizure frequency compared to baseline) at more than 12 months of treatment, was reported in 35% of patients starting GAB, including 6% who remained seizure free. The results demonstrated the efficacy and tolerability of GAB in children with difficult to treat epilepsies, and a good response to treatment beyond 12 months, in both focal and generalised epilepsies.

4-Amino-5-benzoyl-2-(4-methoxyphenylamino)thiazole (DAT1): a cytotoxic agent towards cancer cells and a probe for tubulin-microtubule system.

Microtubule binding drugs are of special interest as they have important roles in the modulation of cellular functions and many of them act as anticancer agents. 4-Amino-5-benzoyl-2-(4-methoxyphenylamino)thiazole (DAT1) was identified as one of the active compounds from a series of diaminoketothiazoles in a cell-based screening assay to discover cytotoxic compounds. DAT1 shows cytotoxicity with GI(50) values ranging from 0.05 to 1 microM in different malignant cell lines with an average value of 0.35 microM. It blocks mitosis in the prometaphase and metaphase stages. In HeLa cells, DAT1 blocks the spindle function by disturbing spindle microtubule and chromosome organization. The drug also inhibits assembly of brain microtubules and binds tubulin specifically at a single site with induction of fluorescence. The dissociation constant of DAT1 binding to tubulin was determined as 2.9+/-1 microM at 24 degrees C. The binding site of DAT1 on tubulin overlaps with that of the conventional colchicine-binding site. DAT1 can thus be considered as a lead compound of a new class of small molecules and this study can be used as a step to develop potent antimitotic agents for the control of cytoskeletal functions and cell proliferation. It would also be an interesting probe for the structure-function studies of tubulin-microtubule system.