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Biomedical subjects

R A Prince

Publications and source records attributed to R A Prince.

At least 19 recordsLinked to original sources
PubMed1992

Stability of ondansetron hydrochloride in injectable solutions at -20, 5, and 25 degrees C.

The stability of ondansetron hydrochloride in 5% dextrose injection and in 0.9% sodium chloride injection when stored frozen, refrigerated, and at room temperature was studied. Solutions of ondansetron 0.03 and 0.3 mg/mL (as the hydrochloride salt) were prepared by adding 1.5 or 15 mg of the drug to 50-mL minibags containing 5% dextrose injection or 0.9% sodium chloride injection. All solutions were prepared in triplicate, and each container was tested in duplicate. Testing at the time of preparation and at each subsequent test interval included visual inspection of color and clarity, determination of pH, and a stability-indicating high-performance liquid chromatographic assay to measure the ondansetron concentration. Conditions assessed included storage at -20 degrees C for two weeks to three months, 5 degrees C for 7-14 days, approximately 25 degrees C for up to 48 hours, and various combinations of these conditions. The concentration of ondansetron in each solution remained above 90% of the original concentration at each observation time under all storage conditions. No changes in color or clarity were observed, and there were only minor changes in pH. Ondansetron 0.03 and 0.3 mg/mL in 5% dextrose injection or 0.9% sodium chloride injection was stable when stored (1) for up to three months at -20 degrees C, followed by up to 14 days at 5 degrees C and by 48 hours at 25 degrees C and (2) for up to 14 days at 5 degrees C, followed by up to 48 hours at 25 degrees C.

Drug Stability↗
PubMed1991

Alpha interferon gene deletions in adults, children and infants with acute lymphoblastic leukemia.

DNA from 76 cases of acute lymphoblastic leukemia (ALL) was tested with a cDNA probe encoding the alpha 2B interferon (IFN) gene transcript. Deletions were found in three of ten pre-B, three of 21 T-cell, four of 22 common and one of 23 null ALL cases. Amongst those with null ALL were 20 infants, most with characteristic translocations, none of whom had deletion of alpha IFN genes. The results confirm that alpha IFN gene deletions may occur without visible abnormalities of chromosome 9p and show that they occur across a wide range of ALL phenotypes. The results suggest that alpha IFN gene deletions may be rare events in null ALL of infants but their incidence and cellular consequences remain unknown.

Adult↗
PubMed1989

Effect of quinolone antimicrobials on theophylline pharmacokinetics.

The purpose of the research was to ascertain the comparative differences of quinolone antibiotics on theophylline pharmacokinetics. Eight healthy male volunteers were randomly assigned to four treatments. Each was administered norfloxacin (NOR) 800 mg/d, ciprofloxacin (C) 1 g/d, nalidixic acid (NAL) 2 g/d and placebo (P) for 7 days. On the seventh day of each treatment, theophylline (5 mg/kg) iv was administered. The elimination half-life (T 1/2), total body clearance (CL) and volume of distribution at steady state (Vss) of theophylline were calculated using model-independent methods. ANOVA for repeated measures was used for data comparisons. The mean (SD) theophylline results were: CL l/kg/h--NOR .038 (.006), C .033 (.006), NAL .045 (.008), P .044 (.007); T 1/2 h--NOR 9.2 (1.8), C 10.6 (1.8), NAL 8.3 (1.8), P 7.5 (1.4). Theophylline Vss differences by treatment were not significant. NOR and C significantly decreased theophylline's clearance and the clearance change can be of clinical significance.

Adult↗
PubMed1989

Influence of endotoxin-induced fever on the pharmacokinetics of theophylline in the rabbit model.

To assess fever-induced changes in theophylline pharmacokinetics in the rabbit model, six healthy, male, New Zealand white rabbits were studied using a randomized, matched-pair design. In treatment 1, 15 mg/kg of theophylline was infused into the left marginal ear vein, and several blood samples were collected from the opposite ear for 10 hours. Treatment 2 was conducted in an identical manner, except 20 to 40 micrograms/kg of Escherichia coli endotoxin was injected into the left marginal ear vein to induce fever. The majority of the rabbits had slight decreases in the slowest disposition rate constant and increases in the volume of distribution at steady state; however, total body clearance was only minimally (5%) changed. No statistically significant differences were noted between these values (Hotelling T2 = 0.32). Given the sample and methods, fever apparently does not affect theophylline pharmacokinetics.

Animals↗
PubMed1987

Penetration of cefotaxime into respiratory secretions.

The objective of this study was to quantitate cefotaxime and its active metabolite, desacetyl cefotaxime, in the distal airways and to compare these levels to concentrations in plasma. Respiratory secretions were obtained from the subsegmental level in 17 adult patients undergoing fiber-optic bronchoscopy within 2 h after receiving four doses of cefotaxime (2 g intravenously every 6 h). In 11 patients, cefotaxime levels measured by high-pressure liquid chromatography in bronchial secretions were below detectable limits (less than 0.5 mg/liter); however, levels of desacetyl cefotaxime exceeded 1.5 mg/liter in 9 of these 11 patients (range, 1.6 to 10 mg/liter). Concentrations of desacetyl cefotaxime in lung secretions (6.9 +/- 0.85 [standard error] mg/liter) was 77% of mean levels of desacetyl cefotaxime in plasma (8.9 +/- 1.26 mg/liter). In summary, concentrations of desacetyl cefotaxime in bronchial secretions are markedly higher than those of cefotaxime.

Adult↗
PubMed1986

Effects of smoking on nortriptyline plasma concentrations in depressed patients.

The pharmacokinetic parameters of half-life, volume of distribution, and steady-state nortriptyline plasma concentration normalized to a 100-mg/day maintenance dose were calculated in nine smokers and 15 nonsmokers. The mean normalized total nortriptyline concentration for the smokers of 118 +/- 33 ng/ml was significantly lower than the nonsmokers' mean value of 158 +/- 35 ng/ml. The mean normalized free plasma concentrations for the smokers of 11.4 +/- 3.5 ng/ml was not different from the nonsmokers' mean concentrations of 11.5 +/- 2.6 ng/ml. The smokers had a slightly higher percentage free drug values of 10.2 +/- 4.0% (p = 0.08) as contrasted to 7.4 +/- 1.5% free nortriptyline for the nonsmokers. The nortriptyline half-life figures for both the free and total drug concentrations did not differ. Multiple linear regression analysis utilizing age, smoking status, sex, liver function, and the presence or absence of enzyme-inducing or -inhibiting drugs as the potential independent variables and percentage free nortriptyline or total nortriptyline concentration as the dependent variable, found that smoking status explained 21% of the variation in the percentage free nortriptyline in the patients and 26% of the variation in the total nortriptyline concentrations. These preliminary data suggest that smokers ideally should be dosed at the lower end of the nortriptyline therapeutic range, whereas nonsmokers should be dosed at the upper end to maximize the antidepressant effect and minimize adverse effects.

Adolescent↗
PubMed1986

The utility of a single-point dosing protocol for predicting steady-state lithium levels.

Two methods for predicting steady-state serum lithium level were compared prospectively in in-patients suffering from affective disorder. A single-point prospective administration model that required a single 24-hour serum lithium level, following a test dose produced statistically similar predictions of the observed steady-state lithium levels as did a model that required 12- and 36-hour levels. However, the latter two-point method produced significantly more accurate predictions from clinical interpretation. Although the two-point approach is preferable, the single-point method is clinically acceptable if its limitations of accuracy are taken into consideration.

Adult↗
PubMed1984

Prospective evaluation of two lithium maintenance dose schedules.

A prospective method for recommending lithium carbonate maintenance doses for patients requiring the drug either prophylactically or for acute mania has been previously described. Of 18 patients who required prophylactic lithium levels between 0.40 and 0.89 mEq/liter, the maintenance dose equation achieved the predefined therapeutic range in 15 (83%) cases. Of 20 patients requiring lithium concentrations between 0.90 and 1.30 mEq/liter for the treatment of acute mania, 17 (85%) attained the therapeutic range after receiving the recommended maintenance dose. The authors discuss the factors that limit the usefulness of this prospective dosing protocol.

Adult↗
PubMed1982

Comparative trial of benzoyl peroxide versus benzoyl peroxide with urea in inflammatory acne.

Improvement in vehicle design may improve the delivery of drugs to the target site. A clinical trial was performed to evaluate an improved vehicle for topical benzoyl peroxide. Thirty-nine subjects participated in a split-face, double-blind trial of topical benzoyl peroxide 5 percent versus benzoyl peroxide 5 percent in 8 percent urea. All subjects had grade II or III acne as described by Pillsbury. Study solutions were randomly assigned to a selected side of the subject's face and applied twice a day to the appropriate side of the face for eight weeks. Total and inflammatory lesion counts were performed by the same investigator during the eight weeks of study at biweekly intervals. No overall differences in the response to the study preparations were observed when assessed objectively and subjectively.

Acne Vulgaris↗
PubMed1981

Clinical trial of topical erythromycin in inflammatory acne.

Sixty-nine informed subjects participated in a split-face, double-blind trial of topical erythromycin base 2% in Vehicle/N versus Vehicle/N alone. All subjects had grades II or III acne as described by Pillsbury. Study solutions were assigned to a randomly selected side of the subject's face. Solutions were applied twice daily. Inflammatory lesion counts were performed by the same investigator during the eight weeks of study at biweekly intervals. The difference in inflammatory lesion counts from beginning to end of study for each side of the face was compared utilizing Student's paired t-test. There was not a statistically significant difference in mean inflammatory lesions at the end of eight weeks (D = 1.46, t = 1.36, df 68). There was, however, a significant difference at two and six weeks (D = 2.59, t = 3.72, df 68; D = 1.41, t = 2.03, df 68). Observed differences in lesion counts were not considered to be clinically significant.

Acne Vulgaris↗
PubMed1977

Agranulocytosis associated with procainamide therapy--report of a case.

The case of a 69-year-old woman with procainamide-induced agranulocytosis is reported, and literature reports of 14 other such cases are reviewed. The patients was exposed to procainamide, prescribed for atrial fibrillation, for 26 days, with a daily dose of 1.5 to 4 g and a total dose of 57.5 g. She recovered from agranulocytosis after discontinuation of the drug and hospital treatment for 16 days. Among the reported cases of procainamide-induced agranulocytosis, the daily dosage ranged from 750 mg to 4.5 g; the total ingested dose before agranulocytosis was observed ranged from 36.5 to 316.3 g. Patients treated with procainamide should be instructed to report any soreness of the mouth, throat or gums; unexplained fever; or any symptoms of upper respiratory tract infection. If white blood cell counts indicate bone marrow depression, the drug should be withdrawn and appropriate evaluation begun at once.

Aged↗
PubMed1977

Nitrofurantoin polyneuropathy: report of two cases.

Two case reports of patients who developed a toxic neuropathy associated with nitrofurantoin are presented. In each case the patient had normal renal function and the symptoms abated upon withdrawal of the drug. Although the specific mechanism by which nitrofurantoin causes the neuropathy is still not known, various hypotheses are discussed and the literature is reviewed. The danger of nitrofurantoin administration in patients with impaired renal function is emphasized, and it is stress that early signs and symptoms of peripheral neuropathy be reported and the drug immediately discontinued. Even in the presence of normal renal function, the recommended dosage and duration of therapy should not be exceeded.

Administration, Oral↗