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R C Hatton

Publications and source records attributed to R C Hatton.

26 records · Page 2Linked to original sources
PubMed1984

Comparison of the predictions of one- and two-compartment microcomputer programs for long-term tobramycin therapy.

A retrospective study of patients receiving tobramycin compared the accuracy of predictions of actual trough serum concentrations using two commercially available microcomputer software programs. Twelve patients met the study criteria of intravenous tobramycin treatment for more than 10 days with serum concentration monitoring within the first 5 days and after 10 days of therapy. No patients received dialysis. Twenty-five serum concentrations were compared. Predictions within 0.2 microgram/ml were considered clinically "exact." No significant differences were found by chi-square analysis for any of the four possible choices (p less than 0.3). One of the programs, distributed by Dista Pharmaceuticals, offers a one-compartment model, a two-compartment model, and a two-compartment prenephrotoxic option. SIMKIN, a program marketed by Medical Engineering, Inc., uses a two-compartment model. Overall, the predictions errors were small, but occasionally were clinically significant. Further evaluation of microcomputer programs for therapeutic drug monitoring is necessary to document their impact on predicting drug efficacy and toxicity.

Adult↗
PubMedDate not supplied

Creatine: a review of efficacy and safety.

OBJECTIVE: To provide an overview of the data on the efficacy and safety of the nutritional supplement creatine. DATA SOURCES: Human studies in English in MEDLINE, Current Contents, BIOSIS, Science Citation Index, and the popular media (including a LEXIS-NEXIS search and information from the World Wide Web and lay media) for 1966 to July 1999 using the search terms creatine, creatine supplement#, creatine monophosphate, and creatine NOT kinase. DATA SYNTHESIS: Creatine use is common among professional athletes. Its use has spread to college athletes, recreational athletes, and even children. Most creatine supplement regimens include a loading dose of 20 to 30 grams divided in 4 equal doses for 5 to 7 days, followed by a 2 gram per day maintenance dose. The increased creatine in the muscle may allow larger stores of phosphocreatine to build, and provide extra energy in the form of adenosine triphosphate. Despite the many clinical trials, high-quality research is lacking. Laboratory investigations of endurance isotonic exercises, strength and endurance during isotonic exercises, isokinetic torque, isometric force, and ergometer performance have yielded roughly an equal number of published studies showing a positive effect or lack of effect. Field studies (i.e., on subjects participating in sports activities) are less impressive than laboratory studies. Performance was more often improved for short-duration, high-intensity activities. Reports have linked creatine to weight gain, cramping, dehydration, diarrhea, and dizziness. Creatine may decrease renal function, but only two case reports of this effect have been published. Creatine appears to be well tolerated in short-term trials. CONCLUSION: While creatine may enhance the performance of high-intensity, short-duration exercise, it is not useful in endurance sports. Because commercially marketed creatine products do not meet the same quality control standards of pharmaceuticals, there is always a concern of impurities or doses higher or lower than those on the labeling. Consumers should balance the quality of information supporting the use of creatine with the known and theoretical risks of using the product, including possible renal dysfunction.

Adult↗
PubMedDate not supplied

Accuracy of serum gentamicin concentration predictions generated by a personal-computer software system.

Predictions of serum gentamicin concentration and half-life, using a personal-computer software system (SIMKIN [simulated kinetics]), were compared for accuracy as increasing amounts of patient-specific data were supplied to the computer. Data for a two-year period were collected for patients of a hospital's pharmacokinetic consultation service; the study group included adults who had at least one serum concentration for which time of last gentamicin dose was recorded. Input variables were age, weight, height, sex, serum creatinine concentration, concomitant drugs and diseases, gentamicin dosage, time of infusion, dosing interval, number of doses on each regimen, and time and reported value of all serum gentamicin concentrations. Individualized dosing regimens were calculated on the basis of literature estimates, and half-life and serum concentrations were then estimated for these regimens and compared with actual values. One or two measured serum concentrations were then added to the input data. The computer-estimated half-lives (obtained from single-point or two-point analysis in different dosage intervals) were compared with the half-lives determined from actual serum concentration data. Gentamicin serum concentrations were similarly compared. The computer's ability to predict subsequent serum concentrations improved in sequence for literature-averaged prediction and single-point and multipoint analysis. Accuracy of predicting whether peak concentrations were therapeutic or subtherapeutic and whether trough concentrations were toxic also improved as more patient-specific data were input. SIMKIN appropriately evaluated demographic and laboratory data and adequately predicted gentamicin half-lives and serum concentrations.

Adolescent↗
PubMedDate not supplied

Conversion from intravenous aminophylline to sustained-release theophylline: computer simulation versus in vivo results.

The accuracy of computer-predicted theophylline serum concentrations compared with actual serum concentrations in patients whose drug therapy was being converted from aminophylline infusions to an oral sustained-release theophylline product (Theo-Dur) was measured. The SIMKIN computer program was used to simulate theophylline serum-concentration curves in nine patients receiving an initial dose of sustained-release theophylline at the time their maintenance aminophylline infusions were discontinued. The sustained-release theophylline doses were calculated using individual patient theophylline clearance values to produce mean theophylline serum concentrations in the normal therapeutic range. Pharmacokinetic variables used in the SIMKIN program were derived from individual patients' serum concentrations and average literature values. Theophylline serum concentrations were measured before the initial dose of the sustained-release product and periodically for 12 hours. Mean SIMKIN-predicted serum theophylline concentrations were within 10% of actual measurements 39% of the time, but data from individual patients varied considerably. Two patients had prolonged absorption lag times that could not be explained. Computer-simulation programs using population-based pharmacokinetic variables to predict theophylline serum concentrations must be tested against in vivo measurements to verify their accuracy.

Adult↗