Biomedical subjects

P R Rege

Publications and source records attributed to P R Rege.

10 recordsLinked to original sources

PubMed1999

Chitinosans as tableting excipients for modified release delivery systems.

The term 'chitinosans' embraces the spectrum of acetylated poly(N-glucosamines) ranging from chitin to chitosan. Chitinosans (I), at acidic pH, have protonated amines which can interact with oppositely charged drug ions and, thereby, modify drug release from drug delivery systems. Tablets were compressed from a physical mixture containing salicylic acid (II) as the model drug, I, and magnesium stearate. Five commercial I compounds, varying in degree of deacetylation and molecular weight, were selected. Tablets were compressed at 5000, 10 000, and 15 000 psig using a Carver and a single punch tablet press. The differential scanning calorimetry thermograms provided evidence of I-II interaction in the powder blend. Analysis of variance (ANOVA) indicated that the compression pressure did not significantly affect the crushing strength (CS) or the release profile of II from the I-matrix tablets (P?0.05). Furthermore, the ANOVA also indicated that the tablet press used during manufacture did not affect the above properties (P?0.05); however, the chitinosans significantly affected the CS as well as the release profile of II from I-matrix tablets (P<0.05). This study provides further evidence for the use of commercial I compounds as excipients for use in modified release drug delivery systems.

Acetylation↗

PubMed1998

Development in release testing of topical dosage forms: use of the Enhancer Cell with automated sampling.

The aim of this study was to evaluate an automated method using the Enhancer Cell and compare the release of the corticosteroid triamcinolone acetonide (TA) from commercial semisolid formulations. The method used a modified USP Apparatus 2 using the Enhancer Cell in 200 ml capacity flasks instead of the standard 900 ml flasks. The additional equipment included an adapter plate to position the flasks in the center, a cover to reduce the receptor phase evaporation and smaller sized (1/4 in.) shaft and collets. All products were evaluated prior to their expiration date. Effects of system variables such as the temperature and composition of the receptor medium, stirring speed, and the choice of membrane on the drug release were evaluated. Statistical analysis was carried out using SAS Ver. 6.07 and the slopes and intercepts (of the cumulative release/unit area versus square root of time plots) were compared. TA release was a linear function of the square root of time (P < or = 0.0001), in accordance with Higuchi's model (r2 > or = 0.9 in most cases). Temperature (32 and 37 degrees C) did not affect the drug release (P > 0.32) but a significantly higher release rate was observed (P < or = 0.0001) at 50 degrees C. Stirring speed (50, 100, 200 rpm) (P > 0.26) and receptor media composition (38 and 76% ethanol) (P > 0.68) did not significantly alter the release rates. Membrane selection (regenerated cellulose, polyethylene, and rat skin) was found to be a significant variable (P < or = 0.004). This study demonstrates the use of the Enhancer Cell as an automated quality control tool in the in vitro release testing procedure for semisolid drug formulations.

Administration, Topical↗

PubMed1975

Carcinoma in isolated bladder after ileoconduit diversion.

A thirty-six-year-old Caucasian male paraplegic of sixteen years' duration, who was found to have carcinoma of the bladder about twenty-three months after an ileoconduit diversion had been performed for decompensated neurogenic bladder is presented. Chronic infection and residual urine may irritate or accelerate the process of neoplastic change in transitional epithelium. Obviously the supravesical diversion of urine in this patient did not avoid the occurrence of cancer. A plea is made for periodic checks using bladder exfoliative cytology and cystoscopy of the isolated bladder for early detection of vesical neoplasm.

Adult↗

PubMed1975

Renal calculi and biochemical abnormalities. In children with myelomeningocele and heoconduit diversion.

Of 38 pediatric cases of ileoconduit urinary diversion of myelomeningocele, 4 with renal calculi are presented. An increased risk of renal calculus formation may be imposed on children with myelomeningocele with ileoconduit urinary diversion especially so in functionally and anatomically abnormal kidneys and in chronic renal infection with urea-splitting bacteria. It is not clear why the ileoconduit procedure should increase the incidence of renal calculi in such children.

Adolescent↗

PubMed1974