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Biomedical subjects

W A Mahon

Publications and source records attributed to W A Mahon.

52 records · Page 3Linked to original sources
PubMed1970

Studies on the absorption and distribution of doxycycline in normal patients and in patients with severely impaired renal function.

Doxycycline, a recently synthesized analogue of tetracycline, was given to 16 patients with normal renal function and to 14 patients with severely impaired renal function. Serum concentrations in the two groups following a single dose were followed after absorption. The rate of clearance from the plasma following a single dose did not differ significantly in the two groups despite low urinary concentrations in patients with renal failure. No accumulation of doxycycline occurred in the serum of three normal patients or of nine patients with renal failure when treated with either 200 mg. daily or 200 mg. initially followed by 100 mg. daily for up to 15 days.

Biliary Fistula↗
PubMed1967

Pneumonia in Indian and Eskimo infants and children. I. A clinical study.

Ninety-seven Indian and Eskimo infants and children who suffered 112 episodes of pneumonia were the subjects of a prospective study carried out at the Charles Camsell Hospital, Edmonton, Alberta, from August 1963 until August 1964. Investigation included viral studies and an evaluation 10 days after admission. The patients were divided into four diagnostic categories and a comparison was made between cases of bacterial and viral origin. The frequency of right-sided disease, particularly of the upper lobe and/or dependent segment involvement, is described. An evaluation of physical signs is attempted. The problem of recurrent pneumonia and the differential diagnosis of tuberculosis in Indian and Eskimo children with pneumonia is discussed.

Adolescent↗
PubMedDate not supplied

Nifedipine gastrointestinal therapeutic system (GITS) for hypertensive patients in a primary care setting: results of the Extended Release Adalat Canadian Trial (EXACT).

Nifedipine gastrointestinal therapeutic system (GITS) is an extended-release dosage formulation that provides sustained blood concentrations of nifedipine over 24 hours. A 20-week, postmarketing surveillance study of the effectiveness and patient tolerability of nifedipine GITS 30 or 60 mg was conducted in the offices of 187 Canadian general practitioners from September 1992 to March 1994. A total of 1700 patients previously or newly diagnosed with mild-to-moderate essential hypertension (sitting diastolic blood pressure, 95 to 114 mm Hg) were included. The 20-week treatment period was completed by 1326 patients. Patients received nifedipine GITS 30 mg initially; the dose could be titrated upward to 60 mg after 3 and 6 weeks. Of all patients entered, 605 (35.6%) reported one or more adverse events. The three most frequently occurring adverse events were headache (12.2%), peripheral edema (8.1%), and dizziness (2.9%). The frequency of adverse events was highest in the first 3 weeks and decreased subsequently. The overall incidence of adverse events was 29.8% in patients receiving 30 mg of nifedipine GITS and 25.3% in those receiving 60 mg; adverse events were the cause of study discontinuation in 12.3% of patients. The overall health status of patients as measured by the SF-36 questionnaire was comparable to that previously reported for healthy individuals. At baseline, mean (+/- SE) systolic/diastolic blood pressure values for all patients were 160.1 +/- 0.4/97.4 +/- 0.2 mm Hg. Final blood pressure readings after 20 weeks of treatment in the 30-mg group (141.5 +/- 0.4/84.8 +/- 0.2 mm Hg) and the 60-mg group (146.6 +/- 0.8/88.8 +/- 0.4 mm Hg) were significantly decreased from baseline. At week 20, the 30-mg dose was sufficient to maintain blood pressure in 74.5% of patients; 25.5% of patients required 60 mg. Subgroup analysis revealed similar responses in patients who had received blood pressure medication before study initiation and those who had not. Response was also independent of age and type of previous antihypertensive therapy. In general medical practice, the 30-mg and 60-mg doses of nifedipine GITS were both effective and well tolerated and had minimal or no negative effects on the overall health status of treated individuals.

Adult↗
PubMedDate not supplied

In vitro inhibition studies of two isozymes of human liver cytochrome P-450. Mephenytoin p-hydroxylase and sparteine monooxygenase.

Human liver preparations were used to screen various drugs for their capability of binding to mephenytoin p-hydroxylase and sparteine monooxygenase, two cytochrome P-450-catalyzed activities that are independently heritable. For this screening, any indication of competitive inhibition by the drug was interpreted as an indication of binding. Among 64 drugs and alkaloids tested, 24 compounds caused inhibition of mephenytoin p-hydroxylation but the inhibition was weak in most cases; by contrast, 40 of the 64 compounds inhibited sparteine oxidation, the inhibition being potent in many cases. The only fairly strong inhibitors of mephenytoin p-hydroxylation were the alkaloid papaverine and the monoamine oxidase inhibitors tranylcypromine and nialamide. The results of these inhibition studies confirm the independence of the two monogenic defects observed in different populations. Metabolism is possibly altered in poor metabolizers of mephenytoin with fewer drugs than in poor metabolizers of sparteine.

Alkaloids↗
PubMedDate not supplied

Metabolism of diazepam in vitro by human liver. Independent variability of N-demethylation and C3-hydroxylation.

The interindividual variability of diazepam metabolism was studied using human livers. The formation of N-desmethyldiazepam (NDZ) and 3-hydroxydiazepam (temazepam, TMZ), was monitored by gas chromatography. In 10 livers, Km values for NDZ and TMZ formation varied independently from each other, each by a factor of 4, from 100 to 400 microM. This variability is consistent with the presence of at least two different cytochrome P-450 species controlling formation of these metabolites. In the same livers, Vmax for NDZ and TMZ production varied 6-fold and 15-fold, respectively.

Anti-Anxiety Agents↗