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M Rangarajan

Publications and source records attributed to M Rangarajan.

42 records · Page 3Linked to original sources
PubMedDate not supplied

Kinetics of permeation and metabolism of alpha-tocopherol and alpha-tocopheryl acetate in micro-Yucatan pig sin.

The objective of this research was to investigate the permeation and metabolism of alpha-tocopheryl acetate (alpha-TAc) and alpha-tocopherol (alpha-T) from solution and emulsion formulations and to delineate the kinetics of such metabolism. Simple formulations containing alpha-TAc and alpha-T were applied to fresh, viable micro-Yucatan skin dermatomed to a thickness of 250-300 microns, as a finite dose in a flow-through diffusion system. The experiments were stopped at time intervals of 2, 6, 12, and 24 hours. At the end of each time interval, the amounts removed by washing, retained in the stratum corneum (SC), and penetrated into the viable skin and receptor were determined by a validated HPLC method. Receptor concentrations were below the limit of detection. alpha-TAc underwent metabolism in pig skin to the active antioxidant alpha-T. The metabolite appeared as early as two hours after application. The extent of metabolism was highest at 6-12 hours after application. No metabolism was detected in the stratum corneum. Delivery of alpha-T from isopropyl myristate (IPM) solution was more efficient than utilization of alpha-TAc from the same solution. Approximately 1.5% of alpha-T yielded the same viable skin concentration as 5% alpha-TAc. Topical application of alpha-tocopherol or its prodrug acetate was capable of enhancing the overall antioxidant capacity of pig skin. The hydrolytic pathway of alpha-TAc leading to the active antioxidant alpha-T could possibly be saturable.

Animals↗
PubMedDate not supplied

Effect of formulation on the delivery and metabolism of alpha-tocopheryl acetate.

The effect of delivery system on the permeation and metabolism of alpha-tocopheryl acetate (alpha-TAc) was studied in micro-Yucatan pig skin, which closely resembles human skin. Various alpha-tocopheryl acetate formulations, including a simple isopropyl myristate (IPM) solution, an o/w emulsion, microemulsions, which differed in their oily phase content, and alcoholic and hydroalcoholic gels were made. A suitable HPLC method was developed and validated to separate and quantify alpha-TAc and alpha-tocopherol (alpha-T). Dulbecco's modified phosphate-buffered saline with 3% bovine serum albumin (DMPBS-BSA 3%) served as the receptor media to ensure tissue viability and to maintain skin conditions. Finite doses (5 microl) of the formulations were applied to viable pig skin using a statistically approved randomized complete block design. Data were analyzed using Tukey's studentized range test, and interday variability was estimated using an F-test. About 70% of the active was recovered from the wash, representing the amount adhering to the surface of the skin. alpha-TAc underwent metabolism in pig skin to the active antioxidant, alpha-T. The identity of the HPLC peaks were confirmed by spiking studies using known standards. The extent of metabolism was found to be formulation-dependent. No alpha-T was, however, detected in the stratum corneum. A higher extent of metabolism was obtained for the IPM solution, a microemulsion containing IPM as the oily phase, and the hydroalcoholic gel, when calculated based on the percent of total alpha-TAc permeated in the viable skin. Metabolism occurred in pig skin to the extent of 15-20% in terms of the total amount of alpha-TAc permeated in the viable skin and stratum corneum. Thus the topical delivery and metabolism of alpha-TAc were found to be dependent on formulation.

Animals↗
PubMedDate not supplied

Laparoscopic jejuno-jejunostomy for afferent loop stasis following truncal vagotomy with posterior gastro-jejunostomy for pyloric stenosis.

A 47-year-old man presented with epigastric pain relieved by bilious vomiting since one month. He had undergone truncal vagotomy with posterior gastrojejunostomy for benign gastric outlet obstruction 2 years ago. Endoscopy showed distension and stasis in the afferent loop, bile gastritis and esophagitis. Laparoscopic Braun jejunojejunostomy relieved his symptoms.

Gastrectomy↗