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Biomedical subjects

A R DiSanto

Publications and source records attributed to A R DiSanto.

At least 19 recordsLinked to original sources
PubMed1979

Decreased tetracycline bioavailability caused by a bismuth subsalicylate antidiarrheal mixture.

Oral coadministration of a single 250-mg tetracycline capsule and 60 ml of a bismuth subsalicylate antidiarrheal mixture reduced tetracycline absorption by 34% without appearing to perturb its absorption or disposition rate. A pronounced increase in intersubject tetracycline absorption variability also was noted. Apparently, the reduction in tetracycline bioavailability previously reported with a kaolin-pectin suspension is not peculiar to kaolin-pectin but can be expected with almost any antidiarrheal whose mechanism of action is adsorptive in nature.

Adult↗
PubMed1979

Double Latin square study to determine variability and relative bioavailability of methylprednisolone.

The variability and relative bioavailability of methylprednisolone tablets were evaluated utilizing a double Latin square crossover design in which each of 20 subjects was given four of five treatments. Three different lots of methylprednisolone tablets exhibited virtually identical absorption, with similar ranges and coefficients of variation of some selected bioavailability parameters indicative of lot-to-lot uniformity in bioavailability. Within-lot and between-lot uniformities in bioavailability also were similar, suggesting that the observed variability in serum methylprednisolone levels was not due to manufacturing process variables. With respect to intra-versus intersubject variability, no differences were found for the absorption rate or terminal half-life. In contrast, between-subject variability associated with extent of absorption was greater than that within subjects. Relative to an aqueous suspension, methylprednisolone tablets were fully bioavailable.

Adult↗
PubMed1978

Pharmacokinetic evaluation of a drug interaction between kaolin--pectin and clindamycin.

The effect of a kaolin--pectin antidiarrheal suspension on the bioavailability of orally administered clindamycin was evaluated by model-dependent pharmacokinetic techniques. Each subject's serum clindamycin concentration--time data in the absence of the kaolin--pectin suspension were fitted to a one-compartment open model with first-order absorption and lag time. The resulting disposition parameters were used to construct individual Wagner-Nelson absorption profiles, expressed as the cumulative relative fraction of clindamycin absorbed versus time following combined antidiarrheal--antibiotic therapy. For each subject, absorption persisted to varying degrees through 14 hr. On the average, the half-time for absorption was prolonged 20-fold (from about 16 min to more than 300 min). In contrast, extrapolation of the individual time courses of relative absorption to infinity revealed that the antidiarrheal had no effect on the extent of clindamycin absorption.

Adult↗
PubMed1978

Influence of kaolin--pectin suspension on digoxin bioavailability.

The effect of a kaolin--pectin suspension on the bioavailability of orally administered digoxin was evaluated when both drugs were given concomitantly and when their time of administration was separated by 2 hr. Coadministration of the antidiarrheal with the cardiac glycoside delayed absorption of the latter and, at the same time, decreased by 62% the amount of drug absorbed. Intersubject variation in digoxin bioavailability also was increased more than twofold. When the kaolin--pectin suspension was given 2 hr before the cardiac glycoside, the digoxin absorption rate was not affected, although its relative extent of absorption was reduced by about 20%. In contrast, when the antidiarrheal was given 2 hr after digoxin, neither the rate nor the extent of absorption of the cardiac glycoside was perturbed. No change in the intersubject variability in digoxin bioavailability was noted whether the antidiarrheal was given 2 hr before or 2 hr after the cardiac glycoside.

Adult↗
PubMed1977

Generic propoxyphene: need for clinical bioavailability evaluation.

Plasma level data on two investigational capsule formulations of propoxyphene with similar physicochemical parameters demonstrate that the formulations have different in vivo bioavailabilities. The potential bioavailability problems with water-soluble drugs and the lack of correlation of in vitro and in vivo parameters for equivalent drug formulations are discussed.

Adult↗
PubMed1976

Unfavorable effect of atropine-diphenoxylate (Lomotil) therapy in lincomycin-caused diarrhea.

In this double-blind, randomized study, 200 normal subjects received a three-day course of one of five treatment regimens: lincomycin hydrochloride monohydrate injection (sterile solution, 300 mg/ml) with two tablets of either placebo, a mixture of atropine sulfate and diphenoxylate hydrochloride (Lomotil), an aspirin-phenacetin-caffeine (APC) combination or the latter with codeine, or an injection of saline with two placebo tablets. Gastrointestinal irritation was most prominent in subjects receiving lincomycin with atropine-diphenoxylate and lincomycin with APC plus codeine (P less than .05). Decreased intestinal motility from atropine-diphenoxylate or codeine may increase the contact time between the lincomycin (or its metabolites) or some developing toxic substances and the mucosal epithelium. The use of atropine-diphenoxylate or codeine in treating lincomycin-induced diarrhea may be questionable.

Administration, Oral↗
PubMed1976

Anorectal pruritus after intravenous hydrocortisone sodium succinate and sodium phosphate.

A double-blind study demonstrated that single intravenous doses of 100, 200, or 400 mg of hydrocortisone sodium succinate and hydrocortisone sodium phosphate were similar in eosinophil suppression, elevation of glucose, white blood count differential shifts (polymorphonuclear cells, lymphocytes, and monocytes), and urinary excretion of sodium and potassium but not in incidence of side effects. More subjects receiving hydrocortisone sodium phosphate experienced systemic or localized adverse effects than those receiving hydrocortisone sodium succinate. The most common side effect was burning or itching in the anorectal area, which occurred in 16 of 18 subjects medicated with hydrocortisone sodium phosphate, in 1 subject of 6 treated with placebo (saline), and in none who received the sodium succinate. The effect is attributed to the phosphate steroid and appears to last as long as it takes to convert to cortisol.

Adult↗
PubMed1976

Phenylbutazone.

Explore the source record for details and available documents.

Biological Availability↗
PubMed1976

Clinical bioavaiability of nitrofurantoin--a case of bioinequivalence.

In a crossover study of the bioavailability of marketed nitrofurantoin tablets, there were significant differences in the urinary excretion of nitrofurantoin suggestive of bioavailability problems with this drug. Standard in vitro assessments of dissolution rate and disintegration time were not correlated with bioavailability and failed to detect 3 to 18 fold differences in the amount of nitrofurantoin absorbed. In fact, four lots, made by the same manufacturer had almost identical in vitro measurements (dissolution rate; distinegration time), yet two of these lots were only 6.6 and 26% as available as the reference nitrofurantoin product, and two others were comparatively available. The need for the development of an in vitro - in vivo correlation for control of lot to lot uniformity has clearly been demonstrated for nitrofurantoin. Such correlations must include tests other than those presently required.

Adult↗
PubMed1976

Intersubject variation of warfarin binding to protein in serum of normal subjects.

The protein binding of warfarin was determined in the serum of 18 normal adult subjects (8 males and 10 females). A statistically significant negative correlation between free fraction of warfarin and albumin concentration was found. The free fraction of warfarin in the serum of women was significantly larger than that in the serum of men, apparently due to the lower albumin concentration in the serum of women.

Adult↗
PubMed1975

Antibiotic batch certification and bioequivalence.

All antibiotics marketed in the United States must undergo batch certification by the Food and Drug Administration. It is often assumed that the different brands of a particular antibiotic that pass in vitro batch certification tests have equal in vivo bioavailability. The fallacy of this assumption is clearly supported for commercially available lots of tetracycline hydrochloride that had passed batch certification tests yet had different serial serum concentrations.

Administration, Oral↗