The effect of inhaled verapamil on resting bronchial tone and airway contractions induced by histamine and acetylcholine in normal and asthmatic subjects

In man, the influence of calcium entry blockers (CEB) on nonspecific bronchial sensitivity and resting bronchial tone is controversial. In 10 asthmatic and 8 normal subjects we recorded specific airway conductance (Gaw/VL) and flow volume loops before, 30, 60, and 90 min after the inhalation of saline, 10 (V10) and 20 mg (V20) of verapamil. The dose of inhaled histamine and acetylcholine producing Gaw/VL of -40% (PD40H and PD40ACH, respectively) with and without pretreatment with saline, V10, and, in 15 subjects, V20 was also determined. We measured plasma verapamil concentrations immediately after the end of nebulization of V10 and V20, and 30 and 60 min later. In normal subjects, V10 and V20 produced a maximal % delta Gaw/VL of 22.30 (+/- 19.50) and 33.00 (+/- 15.82), respectively (p less than 0.05). In asthmatics, V10 and V20 produced comparable % delta Gaw/VL of 22.00 (+/- 22.50) and 38.60 (+/- 38.60), respectively. This bronchodilating effect involved predominantly the large airways, persisted for 60 to 90 min, was reproducible, affected only some subjects (11 of 18), and was independent of the resting Gaw/VL, degree of bronchial sensitivity to H and ACH, and the time course of plasma verapamil concentration. The latter reached a maximum of 24.3 +/- 7.1 ng/ml after V20. In both normal and asthmatic subjects, saline or V10 did not significantly alter PD40H and PD40ACH. In normal subjects, pretreatment with V20 increased PD40H 5.3 times and PD40ACH 3.22 times (p less than 0.05). Except in 2 asthmatics, in whom V20 decreased PD40 and PD40ACH, it increased significantly PD40ACH (dose ratio: 3.15, p less than 0.05) but not PD40H.(ABSTRACT TRUNCATED AT 250 WORDS)     

Retrospective study of the hepatic safety profile of patients concomitantly treated with caspofungin and cyclosporin A

BACKGROUND: Mild, transient alanine aminotransferase (ALT) elevations were seen in Phase I studies of caspofungin and cyclosporin A (CsA). METHODS: We conducted a retrospective chart review at four sites to characterize the hepatic safety in patients receiving > or =1 day of both drugs over a 20-month period. Investigators assessed reasons for discontinuing concomitant therapy and the presence/etiology of any hepatotoxicity. RESULTS: Forty patients receiving concomitant therapy for 1-290 days (median 17.5 days) were identified. Although common, liver enzyme abnormalities were frequently attributed to other comorbidities or medications. ALT and/or aspartate aminotransferase (AST) elevations occurred in 14 patients (35%). Five had AST elevations at least possibly related to caspofungin/CsA, but none were >3.6 times the normal upper limit. No ALT elevations were related to caspofungin/CsA. Two of 4 patients had discontinuation of therapy because of hepatotoxicity possibly related to caspofungin/CsA. No serious adverse events occurred because of caspofungin. CONCLUSIONS: These data do not suggest a significant risk of clinically relevant hepatotoxicity with concomitant caspofungin/CsA.     

Mechanism of Cisplatin Ototoxicity: Antioxidant System

Abstract: The dose and duration limiting toxic effects of cisplatin are ototoxicity and nephrotoxicity. While several studies have attempted to shed some light on the causes of nephrotoxicity, the reasons for ototoxicity induced by cisplatin are poorly understood. Therefore, this investigation was undertaken to delineate the potential mechanisms underlying cisplatin ototoxicity. The role of glutathione (GSH), oxidized glutathione (GSSG) and malondialdehyde levels, and antioxidant enzyme activities [superoxide dismutase, catalase, GSH peroxidase, and GSH reductase] were examined in cochlear toxicity following an acute dose of cisplatin. Male Wistar rats were treated with various doses of cisplatin. Pretreatment auditory brain stem evoked responses (ABR) were performed and then post-treatment ABRs and endocochlear potentials were also performed after three days. Acute cochlear toxicity (ototoxicity) was evidenced as elevated hearing thresholds and prolonged wave I latencies in response to various stimuli (clicks and tone bursts at 2, 8, 16 and 32 kHz) on ABRs. The endocochlear potentials were reduced (50% control) in cisplatin-treated rats as compared to control animals. The rats were sacrified and cochleae isolated. The GSH, GSSG and malondialdehyde levels, and antioxidant enzyme activities were determined. Cisplatin ototoxicity correlated with a decrease in cochlear GSH [0.45±0.012 nmol/mg] after cisplatin administration compared to 0.95±012 nmol/mg in control cochleae (P<0.05). Superoxide dismutase, catalase activities and malondialehyde levels were significantly increased in the cochleae of cisplatin injected rats. Cochlear GSH-peroxidase and GSH reductase activity significantly decreased after cisplatin administration. Alterations in the activity of antioxidant enzymes, an increase in malondialdehyde levels, and depletion of cochlear GSH suggest a role for reactive oxygen species mediated damage of the cochlea in cisplatin toxicity. These biochemical changes were accompanied by the elevation of ABR threshold that appears to correlate well with alterations in antioxidant systems which could be the cause of cisplatin ototoxicity.     

Comparison of automated and manual methods of syringe filling

A study to measure the time and cost associated with an automated and a manual method of syringe filling is reported. A stopwatch was used to measure the time needed by an experienced pharmacy technician to prepare batches of 200 syringes of each of seven drugs by a manual method and an automated method, the Multi-Ad Fluid Dispensing System. For each drug and method, time-and-motion data were collected during the preparation of four batches. The accuracy of each method was determined by dividing the actual by the expected number of syringes filled per batch. Material costs were calculated by summing the contract costs of the necessary equipment. The total cost of each method was determined by adding the labor and material costs. For all the drugs, the mean total time required to prepare one batch of syringes by the automated method was significantly less than that for the manual method. There was no significant difference in accuracy between methods for any of the drugs. The annual labor costs of the automated and manual methods were $4056 and $5761, respectively, and the annual material costs were $3364 and $2260, respectively. The total annual cost of the automated method was $7419, compared with $8021 for the manual method. The Multi-Ad system was significantly faster and somewhat less costly overall than a manual method for batch preparation of syringes of seven drugs.     

Effect of exercise on propranolol pharmacokinetics

Summary The effect of submaximal exercise on the pharmacokinetics of low dose intravenous propranolol was studied in 15 healthy human subjects.There was a wide individual variation in the results for each subject and a large difference in the degree of changes with exercise. The effect of exercise on the pharmacokinetics of propranolol, a flow limited drug, is marked but variable.This phenomenon may have profound effects on patients taking the drug regularly who exercise intermittently and drug doses may have to be adjusted.