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A Martin

Publications and source records attributed to A Martin.

At least 811 records · Page 45Linked to original sources
PubMed1980

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Abortion, Legal↗
PubMed1980

Extended Hildebrand solubility approach: solubility of theophylline in polar binary solvents.

A quantitative approach is presented for predicting solubilities of crystalline compounds in binary solvent systems. The solubility of theophylline in mixed solvents consisting of dioxane and water was determined at 25 +/- 0.1 degrees. The solubilities across this range of polar solvents were back-calculated using a technique involving an interaction energy term, W. This parameter is regressed against a polynomial expression in delta 1, the solubility parameter for the mixed solvents. Except for the end-points, solubilities were predicted within less than 12% and with considerably better accuracy in most cases. The new approach modifies the well-known Hildebrand solubility equation to make it applicable to polar systems. Although the method may be used with solutes in pure solvents, its greatest application appears to be the prediction of drug solubility in binary solvent mixtures.

Mathematics↗
PubMed1980

Extended Hildebrand approach: solubility of caffeine in dioxane-water mixtures.

The solubility of caffeine in various dioxane-water mixtures was analyzed in terms of solute-solvent interactions using a modified version of the Hildebrand treatment for regular solutions. The solubility equation employs a term (W) to replace the geometric mean (c1c2)1/2, where c1 and c2 are the cohesive energy densities for the solvent and solute, respectively. The new equation provides an accurate prediction of solubility once the interaction energy, W, is obtained. In this case, the energy term is regressed against a polynomial in delta 1 of the binary mixture. A quartic expression of W in terms of the solvent solubility parameter was found for predicting the solubility of caffeine in dioxane-water mixtures. The expression yields an error in mole fraction solubility of less than 3%, a value approximating that of the experimentally determined solubility. The one exception to a good fit is near the maximum solubility, where a depression or valley occurs between the two peaks in solubility data; at this point, the theoretical equation predicts the solubility within approximately 9%. The new model also may be used to estimate the solubility of drug molecules employing the volume fraction of water in the solvent mixture instead of the composite solubility parameter, delta 1. The method has potential usefulness in preformulation and formulation studies during which solubility determination is important for drug design.

Caffeine↗
PubMed1980

Disposition of Dibekacin in patients undergoing haemodialysis.

The pharmacokinetics of Dibekacin were studied in 10 patients with terminal renal impairment (creatinine clearance < 5 ml/min) undergoing haemodialysis sessions lasting 4 h. The dialyzers were either the Gambro Lundia Major 13.5 or the Ultra Flo II 1.4., and the patients were divided into two groups according to the dialyzer used. Blood flow varied between 250 and 280 ml/min and dialyzate flow between 450 and 600 ml/min. All patients received a single i. v. dose of Dibekacin 1.5 mg/kg at the beginning of the dialysis session. The concentration of the antibiotic at the input and the output of the dialyzer were determine microbiologically by a plate diffusion method using B. subtilis as the test organism. The intravenously administered antibiotic followed an open two-compartment kinetic model. The type of dialyzer used did not influence the dialysis of Dibekacin. Haemodialysis significantly increased the elimination rate of the antibiotic with respect to the interdialysis periods. The plasma half-life in the slow disposition phase fell from 30 h in the interdialysis period to 4.0 h during dialysis sessions. From the calculated pharmacokinetic parameters, a dosage regimen for this kind of patient is proposed.

Adolescent↗
PubMed1980

Correlation between clinical and radiological diagnosis for fractures and dislocations in an accident department.

Clinicians and radiologists agreed on the presence or absence of fracture or dislocation in 897 of 1011 cases (89%). The agreement was closer in cases that were thought on clinical grounds to show no injury. We think the high incidence of agreement in this group should help to reduce the number of radiographs used in an accident department. Further analysis of the results indicates which areas of the body have most missed fractures.

Adolescent↗
PubMed1980

Treatment of chronic atrial fibrillation in the elderly, assessed by ambulatory electrocardiographic monitoring.

This study concerns 8 elderly patients with age-related chronic atrial fibrillation that required control of the ventricular response. The effects of oral administration of placebo, pindolol, verapamil, digoxin and digoxin + pindolol were assessed (each for a week) during three daily activity and sleep sessions, over a six-week period. Cardiac rhythm was monitored by taped electrocardiograms. Either digoxin or pindolol was effective, but digoxin was the best tolerated of all the drugs. A combination of pindolol and digoxin reduced the maximum ventricular rate without further depression of the minimum ventricular rate. Digoxin seems to be well tolerated in the control of atrial fibrillation in the elderly, and beta blockade may be a useful therapeutic adjunct.

Aged↗
PubMed1980

Correlation of in vivo bioavailability of erythromycin stearate tablets with in vitro tests.

Correlations between the bioavailability parameters for erythromycin stearate tablets from five manufacturers and in vitro tests of these tablets were examined using forward (stepwise), multiple linear regression analysis. Bioavailability parameters were determined in clinical studies employing a balanced, incomplete block design. In vitro tests used disintegration, dissolution, and dissolution/dialysis as the independent variables in regression equations. Significant correlations were found between linear combinations of these parameters and the time of peak and the peak serum levels. The inclusion of an in vitro disintegration test to describe peak serum levels of erythromycin is noteworthy since it has been suggested that disintegration tests are of less value than dissolution techniques employed in the present investigation may be useful for selection of appropriate physicochemical tests for continued monitoring of the bioavailability of erythromycin stearate tablets.

Biological Availability↗