Biomedical subjects

E L Parrott

Publications and source records attributed to E L Parrott.

At least 37 records · Page 2Linked to original sources

PubMed1980

Influence of viscosity on absorption from nitrofurantoin suspensions.

Nitrofurantoin, 200 mg, was administered orally to 11 subjects in an aqueous reference dispersion and in five suspensions having the same rheogram. Algin, carbomer, guar gum, methylcellulose, and colloidal magnesium aluminum silicate were the five suspending agents employed. Complexation was demonstrated by dialysis between nitrofurantoin and methylcellulose and between nitrofurantoin and carbomer; however, physiological availability was not altered by the interaction. The viscosity increase slowed absorption and urinary excretion, thus delaying the time of the maximum excretion rate without a decrease in bioavailability. A clinically acceptable urinary nitrofurantoin concentration was maintained for at least 2 hr longer by a viscosity increase.

Absorption↗

PubMed1980

Measurement of film-coating adhesiveness.

A modified balance was used to measure the adhesive force between the film coating and the tablet surface of 10 commercial film-coated tablets. The adhesiveness or force required to remove the film coating from a unit area of tablet surface ranged from 1.06 to 4.67 x 10(4) Nm-2. Measurement of at least eight film coatings from the sides of four tablets was calculated to be required to obtain a result with 95% confidence. The method also was useful in studying the influence of solvents and humidity on bonding of the film coating to the tablet.

Adhesiveness↗

PubMed1978

Effects of compression force, particle size, and lubricants on dissolution rate.

The effects of compression force, particle size, and lubricant concentration on the dissolution rates of compressed disks of salicylic acid, aspirin, and an equimolar mixture of aspirin and salicylic acid were investigated. Compression forces from 450 to 9100 kg had no effect on dissolution rates. With 5% starch incorporated into an equimolar mixture of aspirin and salicylic acid, the dissolution rates were independent of compression forces from 910 to 9100 kg. A 10-fold change of particle size of the materials being compressed did not affect the dissolution rates. An increase in the concentration from 0.1 to 5% of calcium stearate, glyceryl monostearate, magnesium stearate, and stearic acid progressively slowed the dissolution rate. An increase in the concentration from 0.1 to 5% talc and polyethylene glycol 4000 did not affect the dissolution rates. An increase in the concentration of starch from 0.1 to 5% progressively increased the dissolution rates.

Aspirin↗

PubMed1977

Rectal absorption of nitrofurantoin.

The adsorption in humans of nitrofurantoin from seven suppository bases was studied using urinary excretion measurements. Rectal absorption was poorer than GI absorption. The administration of 400 mg of nitrofurantoin in a polyethylene glycol-polysorbate 80 suppository base and in a polyethylene glycol-silica suppository based provided an adequate urinary concentration of nitrofurantoin. Persons who cannot tolerate orally administered nitrofurantoin due to gastric upset could receive nitrofurantoin therapy rectally.

Administration, Oral↗

PubMed1976

Dissolution of two-component solids.

The dissolution rates of compressed two-component mixtures were investigated. A good correlation between the composition of the solid and its observed dissolution rate was demonstrated by regression analysis. A model for dissolution was applied to compressed mixtures of aspirin-salicylic acid, aspirin-phenacetin, phenacetin-caffeine, and aspirin and caffeine (the last mixture complexes in solution).

Chemistry, Pharmaceutical↗

PubMed1975

Influence of particle size on rectal absorption of aspirin.

The rectal absorption of aspirin from theobroma oil suppositories was studied in seven human subjects using urinary excretion measurements. The effect of particle size on the excretion rate and cumulative amount of total salicylate excreted was demonstrated by the administration of a 600-mg dose as powdered aspirin and as aspirin disks having 0.023 as much surface as powdered aspirin. In vitro dissolution profiles of aspirin from the suppositories were studied. By the NF XIII Method II, the time required for 50% of the aspirin to dissolve from the suppository was 50 and 100 min for the powdered aspirin and the aspirin disks, respectively. In the bioavailability study, the diffusion equilibrium was attained at approximately 4-5 and 9-10 hr after the rectal administration of powdered aspirin and aspirin disks, respectively. No correlation was found between bioavailability and the dissolution profiles as determined by the USP XVIII dissolution method.

Adult↗

PubMed1974