Search PubMed⌕ Search

Biomedical subjects

R D Roberts

Publications and source records attributed to R D Roberts.

27 records · Page 2Linked to original sources
PubMed1983

Low-melting phenytoin prodrugs as alternative oral delivery modes for phenytoin: a model for other high-melting sparingly water-soluble drugs.

Phenytoin is a high-melting, weakly acidic, and sparingly water-soluble drug. Because of these physicochemical properties, phenytoin is subject to erratic bioavailability in a variety of dosage forms both in its acidic as well as sodium salt forms. A homologous series of 3-acyloxymethyl derivatives of phenytoin (acetyl through decanoyl) were synthesized and various physicochemical properties measured. The prodrugs were more readily soluble in various metabolizable glycerol esters such as tributyrin, trioctanoin, and triolein than phenytoin. The solubility of the prodrugs in the various organic vehicles studies was closely correlated to the melting point of the prodrug: the lower the melting point the greater the solubility. The cleavage rates of the prodrugs in plasma and tissue homogenates followed a parabolic relationship with chain length. The prodrug, 3-pentanoyloxymethyl-5,5-diphenylhydantoin when administered in tributyrin gave superior oral phenytoin bioavailability in rats when compared with sodium phenytoin administered as an aqueous solution.

Administration, Oral↗
PubMed1983

Effects of sarcoid and steroids on angiotensin-converting enzyme.

Serum angiotensin-converting enzyme (ACE) has been claimed to be a useful guide in the treatment of pulmonary sarcoidosis. We reviewed the clinical course of 36 patients with sarcoidosis who had ACE levels determined on 2 or more occasions during the course of treatment with prednisone for a total of 55 paired observations. There was a clinical deterioration in 13 instances. Of these 13, there was a rise in ACE level in only 7. There was a clinical improvement in 19 instances. Of these 19, only 12 had a fall in ACE level. There was a negative correlation (r = -0.80) between changes in steroid dose and serum ACE level. Of 23 instances where steroids were increased, there was a fall in ACE level. Thus, ACE levels were not useful for following disease activity in patients during a change in medication.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Beyond competition.

Hospitals and individuals who form lasting symbiotic relationships that leave both parties intact as viable adversaries will outperform both their non-cooperative and their non-competitive rivals.

Conflict, Psychological↗