Clinically important adverse effects and drug interactions with H2-receptor antagonists: an update.

The H2-receptor antagonists cimetidine, ranitidine, and famotidine are well tolerated, with a low frequency and similar spectrum of adverse effects. The occasional problematic effects that have been associated with these agents include central nervous system symptoms (mental confusion, headache, and depression), rare cases of thrombocytopenia, and cardiovascular events related to the rate of intravenous infusion. Severe renal and hepatic impairment appear to be associated with a higher occurrence of central nervous system effects. Because the H2-receptor antagonists elevate gastric pH, bind to and inhibit the hepatic cytochrome P-450 enzyme system, and undergo renal tubular secretion, competition with other drugs sharing these pathways has resulted in a number of drug interactions, most of which are not clinically significant. The interaction that occurs with theophylline and warfarin when the cytochrome P-450 enzyme system is inhibited by cimetidine and ranitidine requires monitoring. Recent data suggest that administering cimetidine 800 mg at bedtime has less effect on the serum concentrations of warfarin and theophylline than other dosing regimens. Evidence to date indicates that famotidine does not bind to cytochrome P-450 to a significant extent, and interactions with drugs metabolized by this system have not been reported; however, clinical experience with this agent is very limited.

Retrospective evaluation of a pharmacist-managed warfarin anticoagulation clinic.

The effectiveness of a pharmacist-managed warfarin anticoagulation clinic in maintaining therapeutic prothrombin times and preventing hospitalizations secondary to inadequate control of anticoagulation was evaluated. Patients who had received warfarin sodium for at least one year before being referred to the anticoagulation clinic were studied using retrospective chart reviews. Clinical pharmacists provided patient education, monitored patients for hemorrhagic and thromboembolic complications, and adjusted warfarin sodium dosage to maintain therapeutic prothrombin times. The patients' primary physicians retained responsibility for overall care and were consulted by pharmacists regarding complications of anticoagulation and patient unreliability. The percentage of patients requiring hospitalization (39% versus 4%) and the percentage of prothrombin times outside the therapeutic range (35.8% versus 14.4%) were significantly higher during the preclinic phase (before referral to the clinic) than during the clinic phase. Eight patients were hospitalized for hemorrhagic complications and four for thromboembolism during the preclinic phase; only one hospitalization for hemorrhage occurred during the clinic phase. The warfarin anticoagulation clinic staffed by specially trained pharmacists provided improved therapy compared with treatment received by patients before their referral to the clinic.

A guideline for establishing medication teaching groups for schizophrenic patients.

Guidelines for establishing patient-oriented medication teaching groups for the schizophrenic patient are described. The importance of patient education has been well documented, although the effort and subsequent efficacy is still equivocal. Schizophrenic patients have several factors that may lead to drug default. By increasing the patient's database regarding the neuroleptic drug class, an increase in patient compliance may result. An approach to surveying existing programs, soliciting administrative support, addressing the patient, and plans for followup evaluation are outlined in a comprehensive format. It is the author's opinion that this format is highly successful and can be implemented at other institutions.

Clinical pharmacists as allied health care providers to psychiatric patients.

The effect of clinical pharmacy services on the quality and economy of health care provided to psychiatric patients at a Veterans Administration outpatient clinic was evaluated. Twenty-one patients were selected from the Day Treatment Center, of these, 19 patients completed the study. In providing health care to these psychiatric patients, the clinical pharmacist used a systemized approach including data gathering, evaluation, plan of action, and follow-up. In addition, medication groups and weekly staff meetings were incorporated into the patient treatment plan. Following a 3-month study period, the impact of clinical pharmacy services was evaluated. The provision of allied health care to psychiatric patients by clinical pharmacists resulted in a decreased incidence and severity of adverse drug effects, fewer drug use problems, a reduction in the total number of drugs prescribed, improved patient drug knowledge, and reduced expenditures for health care without compromising the patient's mental functioning.