Physician opinion of pharmacist-initiated change from injectable to oral administration of histamine H2-receptor antagonists.

Physicians' knowledge of dosage and cost differences between injectable and oral histamine H2-receptor antagonists (HRAs) and attitudes toward pharmacist-initiated route conversion of HRAs were assessed. A questionnaire was mailed to 491 physicians two months before implementation of a hospital program that allowed pharmacists to use preapproved guidelines to directly change the route of HRA administration. A similar questionnaire was sent to 488 physicians after five months of program operation. The response rate was 36.0% and 37.5% for the first and second surveys, respectively. In both surveys, almost half of the respondents gave incorrect answers or did not know whether dosage should be altered when HRA route is changed, and about 60% underestimated the relative cost of injectable HRAs. Among respondents who were aware of the program, 28% preferred direct pharmacist intervention; 15% of respondents who were unaware of the program had the same preference. Physicians generally responded positively to statements regarding the acceptability of the program and thought that the pharmacist's role in route conversion was appropriate. Many physicians were ignorant of differences in dosage and cost between injectable and oral HRAs. They generally supported allowing pharmacists to change the route of HRA administration from injectable to oral.

Drug dosing during continuous arteriovenous hemofiltration.

An overview of continuous arteriovenous hemofiltration (CAVH), which is an alternative to hemodialysis and peritoneal dialysis in the management of acute renal failure, is provided, and literature concerning drug clearance via hemofiltration is reviewed. CAVH is a slow, continuous process that removes, by convective mass transport, non-protein-bound solutes smaller than 10,000 daltons from blood diverted through an extracorporeal filter. The system provides a creatinine clearance of approximately 10 mL/min. The sieving coefficient of a particular compound reflects its ability to permeate the filter membrane and is primarily influenced by protein binding. Clearance of a compound depends on its sieving coefficient and the ultrafiltration rate. Methods for estimating drug clearance, the amount of drug removed per time interval, and appropriate drug dosages are discussed. Many drugs commonly used in an intensive-care setting, including aminoglycosides, cephalosporins, acyclovir, vancomycin, phenobarbital, ranitidine, and theophylline, can be expected to have a limited but clinically important clearance during CAVH. CAVH substantially enhances the current treatment of acute renal failure; although limited data for specific drugs are available in the literature, drug dosages may be adjusted based on the methods outlined in this review.

Discontinuing antiepileptic therapy.

Prognosis for successful withdrawal of antiepileptics is excellent in selected patients. Studies indicate that therapy should be maintained for at least three seizure-free years before antiepileptics are discontinued. The decision to withdraw medication in an epileptic patient hinges on the likelihood of seizure recurrence and a critical assessment of the benefits of discontinuing therapy as compared with the possible consequences of a recurrent seizure.

Stability of theophylline in human serum and whole blood.

The effect of various storage conditions on serum theophylline results using a fluorescence polarization immunoassay (FPI) method was studied. Two human subjects received sufficient oral theophylline to produce low and high therapeutic serum theophylline concentrations. Aliquots of venous whole blood (without anti-coagulant) and serum from each subject were sealed in polypropylene plastic and glass containers and stored at 4 degrees C and 25 degrees C. Additional aliquots of serum from each subject were stored in glass and polypropylene containers at -20 degrees C. FPI assays were performed on days 0 and 3 for room temperature serum samples, days 3 and 7 for refrigerated serum samples, and days 3, 7, 14, 28, 56, 168, and 336 for frozen serum samples. All whole blood samples were assayed on day 3 after removal of the clot. Some samples were tested using FPI for 1,3-dimethyluric acid, a metabolite of theophylline, and results from spiked samples and samples tested with high-pressure liquid chromatography were compared with FPI results to determine cross-reactivity of the metabolite. No appreciable change in the assayed theophylline values occurred under any storage temperature, nor was there any difference in results from samples stored in glass versus polypropylene containers. At a concentration of 20 micrograms/ml, 1,3-dimethyluric acid produced a cross-reactivity of 3.5% with the FPI system. The FPI method is not affected by storage of samples under the specified conditions over the time period studied.