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Biomedical subjects

J L Colaizzi

Publications and source records attributed to J L Colaizzi.

12 recordsLinked to original sources
PubMed1979

Bioavailability and dissolution behavior of trisulfapyrimidine suspensions.

The bioavailability of seven commercial trisulfapyrimidine suspensions was studied in 14 adult male volunteers. Fifteen blood samples were collected over a 48-hr period following administration of a 1-g dose of each suspension. Serum was assayed for each component (sulfadiazine, sulfamerazine, and sulfamethazine) by high-pressure liquid chromatography. Analysis of variance indicated several significant differences among the seven commercial preparations with respect to Cmax Tmax, and AUC for sulfadiazine, sulfamerazine, and sulfamethazine, The in vitro behavior of each suspension was then studied by the paddle method of the Food and Drug Administration. A 0.5-ml sample was introduced into 900 ml of hydrochloric acid (2.2 x 10(-4) M) at 37 degree and dissolved using a paddle speed of 25 rpm. Samples withdrawn at 15 and 30 min were analyzed by high-pressure liquid chromatography, and the percent of sulfadiazine, sulfamerazine, and sulfamethazine was calculated. Significant correlation was obtained between an in vivo parameter (Cmax for sulfadiazine) and an in vitro parameter (percent sulfadiazine dissolved in 30 min). Results indicate that this method is suitable for the in vitro screening of trisulapyrimidine suspensions.

Adult↗
PubMed1978

Simple high-pressure liquid chromatographic determination of trisulfapyrimidines in human serum.

A simple and rapid high-pressure liquid chromatographic method was developed for the determination of sulfadiazine, sulfamerazine, and sulfamethazine in human serum. After the trichloroacetic acid precipitation of the serum proteins, an aliquot of the supernate is injected into a high-pressure liquid chromatograph equipped with a reversed-phase microparticulate column and a fixed wavelength UV detector. For each of the three components of trisulfapyrimidines, a linear calibration curve was observed in the 1-30-microgram/ml range, with the precision of the assay estimated to be +/- 2% (RSD). Preliminary pharmacokinetic data are also presented.

Chromatography, High Pressure Liquid↗
PubMed1978

Correlation of quinidine absorption with disintegration and dissolution rates.

The dissolution profiles of four commercial quinidine sulfate tablets were determined using the USP rotating-basked dissolution apparatus. Substantial differences in dissolution half-times were noted and compared to previously reported disintegration times, absorption rate constants, and times of appearance of peak serum concentrations. Rank-order correlations were observed among all combinations of in vivo and in vitro parameters, indicating that the absorption rates of these tablets are controlled by both disintegration and dissolution.

Chemistry, Pharmaceutical↗
PubMed1978

Bioavailability of sulfonamide suspensions I: Dissolution profiles of sulfamethizole using paddle method.

A comparative bioavailability study was performed using two commercially available, chemically equivalent brands of sulfamethizole suspension. One gram of each suspension was administered to 12 different subjects following a completely randomized crossover design. Serum levels and derived pharmacokinetic parameters were compared statistically. There were no significant differences in the extent of sulfamethizole absorption from the two suspensions as evidenced by the area under the serum level--time curves. Significant differences (p less than 0.05) in the mean serum levels at 0.5 and 0.75 hr and differences in Cmax and tmax indicated that the absorption rate differed for the two products. In vitro tests including particle-size analysis and dissolution studies were performed. The size--frequency distribution of particles in the suspensions was studied using a resistance particle counter. The dissolution characteristics of the two products were studied using the Food and Drug Administration's paddle method and the spin-filter apparatus. Suspension A had a significantly greater amount of drug dissolved at 15 and 30 min using either method. It also had a greater percentage of particles at the smaller size range, indicating that the greater dissolution rate may be related directly to the decreased particle size. A comparison of the in vivo and in vitro results demonstrated a definite rank-order correlation between the dissolution performance of the two suspensions and the in vivo parameters reflecting the absorption rate. Suspension A had a greater amount of drug dissolved at 15 and 30 min and resulted in higher serum levels at 0.5 and 0.75 hr, a higher Cmax, and a shorter tmax.

Adult↗
PubMed1977

Comparative bioavaiability of four commercial quinidine sulfate tablets.

A comparative bioavailability study was performed using four commercially available, chemically equivalent brands of quinidine sulfate tablets. Two 200-mg tablets were administered to 11 different subjects following a completely randomized crossover design. Serum levels, urinary excretion data, and derived pharmacokinetic parameters were compared statistically. There were no statistical differences in the extent of quinidine absorption from the four brands of tablets as evidenced by the cumulative urinary excretion values and the areas under the serum level-time curves. Significant differences in the mean serum levels at 0.5 and 1 hr and differences in the peak times and absorption rate constants indicate that there was a difference in the absorption rate between Treatments A and D and C and D. A significant difference in the peak times also was noted for Treatments B and C. When mean disintegration times for the four tablet formulations were compared with their values for ka, tmax and mean serum levels at 0.5 and 1 hr, rank-order correlations were observed. A considerable degree of variability in quinidine elimination was noted, with half-life values ranging from 2.71 to 8.12 hr (mean half-life of 5.36 hr).

Adult↗
PubMed1977

Digoxin.

Explore the source record for details and available documents.

Biological Availability↗
PubMed1976

Influence of pH and route of injection on acute toxicity of tetracycline in mice.

Some LD50 determinations for tetracycline hydrochloride in mice were carried out over a range of pH values, using both the intraperitoneal and the subcutaneous routes of injection. Depending on the pH of the formulation, either water or a solvent system of water and 60% (v/v) propylene glycol was employed thus ensuring complete solution of the drug at all pH values tested. Higher LD50 values were obtained with the subcutaneous route than with the intraperitoneal route. With either route of administration, there was a trend toward lowest LD50 value occurrence at the isoelectric pH of tetracycline. Actual statistical significance was achieved for the intraperitoneal route only when LD50 values obtained at the isoelectric pH were compared with either of the more acidic pH values.

Animals↗
PubMed1976

Activated charcoal-carboxymethylcellulose gel formulation as an antidotal agent for orally ingested aspirin.

The in vivo effect on aspirin absorption of a potentially more palatable form of activated charcoal was compared to that of a simple aqueous slurry of activated charcoal. The experimental formulation consisted of 20.0 g of activated charcoal, 2.25 g of carboxymethylcellulose (CMC) and 42.8 ml of water; it was tested with and without chocolate syrup as a flavoring agent added just prior to administration. Six subjects were treated in crossover fashion following an aspirin dose of 972 mg. Total urinary excretion of salicylate was measured over 48 hours. Although all three treatments appeared to be effective in reducing the rate and extent of aspirin absorption, the slurry was significantly more effective in reducing the total amount absorbed than the charcoal-CMC gel with chocolate syrup. The slight difference in effectiveness between the gel formulation with and without the chocolate syrup was not significant.

Adult↗
PubMed1976

Stability of several brands of ampicillin and penicillin V potassium oral liquids following reconstitution.

The stability-time profiles of the active ingredient of five generically equivalent brands of penicillin V potassium for oral solution, and of five generically equivalent brands of ampicillin for oral suspension, were studied. Three controlled conditions were employed-refrigerated, room and elevated temperature-and all the samples were assayed chemically for drug remaining at specific time intervals after reconstitution. The results showed that considerable variations in the initial concentrations of active component existed among the various ampicillin and penicillin products. In one penicillin product the official content requirement was not met. The data also showed that although the labels on each of the commerical penicillin products tested indicate that the reconstituted products may be stored in a refrigerator for 14 days without significant loss of potency, only one penicillin product still met 90% of label claim (minimal potency requirement of the United States Pharmacopeia for dry powder). All ampicillin products tested were stable when stored at the conditions recommended by the manufacturers, but the trihydrate forms exhibited greater stability than the anhydrous forms, probably because of the more rapid dissolution rate of anhydrous ampicillin.

Ampicillin↗
PubMed1975

Bioequivalency of doxycycline products.

The bioavailability of three different brands and three different dosage forms of doxycycline was studied in normal subjects. Single doses, equivalent to 200 mg of doxycycline, were administered to six subjects in a crossover design as the innovator's intravenous solution given orally (Treatment A), the innovator's capsule product (Treatment B), a noninnovator's capsule product (Treatment C), the innovator's oral suspension product (Treatment D), and a second noninnovator's capsule product (Treatment E). All dosage forms contained doxycycline as the hyclate, except the suspension which contained the nonhyclate form. Serum levels were determined periodically over 48 hr, and cumulative urinary excretion was measured concurrently over a 120-hr collection period. No statistically significant differences were observed in any in vivo indicator of bioequivalence when the three capsule products were compared. Consequently, they were judged to be bioequivalent. When these capsule products were compared to the oral solution, no statistically significant differences were observed. However, when the capsules and the suspension were compared, statistically significant differences were found in the rate of absorption. In vitro dissolution tests were also conducted on the three brands of capsules, and times required to achieve 50% dissolution showed rank-order correlation with corresponding absorption rate constants.

Adult↗