Biomedical subjects
Publications and source records attributed to G R Avant.
Acute obstructive cholangitis developed secondary to a common duct stone formed around a silver hemostatic clip, introduced at cholecystectomy two years previously, that had migrated from a long cystic duct remnant. Stone formation around a silk suture is well known, and silver clips in the area of the porta hepatis may constitute a similar hazard.
The radiographic appearance and clinical significance of gastric varices in the absence of esophageal varices and secondary to splenic vein occlusion were studied. Eighteen patients were evaluated through medical records, angiography, and barium studies of the stomach and esophagus. The presence of splenic vein occlusion was determined by arteriography in 18 patients and its etiology confirmed by surgery in 17 patients. This condition should be suspected in patients with chronic abdominal pain, weight loss, and iron deficiency anemia who show fundal polypoid filling defects or prominent gastric folds on an upper GI series.
Under randomized double-blind conditions, 1.00 to 1.67 mg of intravenous physostigmine (Antilirium) reversed sleep induced by administration of 0.102 to 0.238 mg/kg body weight of intravenous diazepam in eight healthy human volunteers. Awakening occurred 330 to 740s after initiation of the physostigmine infusion at a rate of 0.5 mg/min every 4 min. Diazepam plasma levels were not significantly different at the start of either the physostigmine or placebo infusion. Physostigmine did not effect plasma binding of diazepam. Six subjects experienced nausea, and one subject developed an arrhythmia. Physostigmine reverses diazepam-induced hypnosis but causes side-effects requiring cautious administration.
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This study assessed the effect of alcoholic cirrhosis in man and of experimental liver injury in rats on the disposition and elimination of clindamycin. In 7 cirrhotics a statistically significant, although modest, prolongation of clindamycin half-life (T1/2beta) was observed as compared to values in 7 age-matched normal contrals (mean plus or minus SD: 4.46 plus or minus 0.93 hr vs 3.42 plus or minus 0.45 hr, P equals 0.02). This was primarily due to a decrease in clindamycin serum clearance in the cirrhotics, since the volume of distribution of the drug was similar in both groups (P more than 0.05). Serum protein binding of clindamycin was of the order of 79% and was comparable in both groups (P more than 0.05). There was a significant correlation between the T1/2beta of the drug and both total serum bilirubin and SGOT. The T1/2beta of clindamycin was also prolonged in rats with acute hepatic necrosis induced by administration of carbon tetrachloride and those with acute cholestasis caused by common bile duct ligation. These data suggest that liver damage, both chronic and acute, impairs the elimination of clindamycin but that this effect is small.
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This study investigates the separate effects of age and hepatocellular liver disease on the disposition and elimination of diazepam (Valium) in man. The drug was given either by rapid intravenous injection (0.1 mg/kg) or orally (10 mg) to 33 normal volunteers rnaging in age from 15 to 82 yr as well as to 9 individuals with alcoholic cirrhosis, 8 with acute viral hepatitis, and 4 with chronic active hepatitis. In the normal individuals, the terminal plasma half-life of diazepam, (t 1/2 (B)) exhibited a striking age-dependence; at 20 yr the t 1/2 (beta) was about 20 h, but it increased linearly with age to about 90 h at 80 yr. The plasma clearance of diazepam in the majority of the normal subjects was between 20 and 32 ml/min and showed no significant age-dependence. Cigarette smoking did not affect the half-life or the clearance. Additionally, neither the plasma binding (97.4 plus or minus 1.2%, mean plus or minus SD) nor the blood/plasma concentration ratio (0.58 plus or minus 0.16) of diazepam showed any age-related changes (P greater than 0.05). By contrast, analysis of the intravenous data according to a two-compartment open model indicated that both the initial distribution space (V1) and the volume of distribution at steady state [Vd(ss)] of diazepam increased linearly with age (P less than 0.005). The increase in Vd(ss) was secondary to the change in V1. It appears then that the prolongation of t 1/2 (beta) of diazepam with age is primarily dependent on an increase in the initial distribution volume of the drug. The plasma concentration/time course of the metabolite, desmethyldiazepam, was also affected by age. In older individuals, the initial presence and the peak values of desmethyldiazepam were observed later and the metabolite was present in lower concentrations. Despite the profound prolongation of t 1/2 (theta) with age, the constancy of diazepam clearance indicates that drug plasma concentrations will not accumulate any more in the old than the young, and chronic dosage more in the old than the young, and chronic dosage modifications based on pharmacokinetic considerations are unnecessary. Data obtained in patients with liver disease were compared with those found in age-matched control groups. Patients with cirrhosis showed a more than twofold prolongation in the half-life of diazepam (105.6 plus or minus 15.2 vs. 46.6 plus or minus 14.2 h, P less than 0.001).
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Both cimetidine therapy and cirrhosis individually interfere with normal elimination of various drugs. Cimetidine is often prescribed in patients with cirrhosis but there is incomplete data on its effect on drug elimination in cirrhotics. The purpose of this study was to address this issue. Eight stable cirrhotics were studied prior to and following 7 days of cimetidine administration, (300 mg orally q.i.d.). Chlordiazepoxide (Librium), which is eliminated by the liver after demethylation, and indocyanine green, which is removed by the liver without biotransformation, were used as probes. Consistent with the concept that cimetidine interferes with drug metabolism by inhibiting microsomal oxidation, chlordiazepoxide clearance in the cirrhotics was inhibited by cimetidine (p less than 0.05), but indocyanine green clearance was unaffected. As shown by us previously (Roberts, R. K. et al., Gastroenterology 1978; 75:479-485), untreated cirrhotics had substantially lower chlordiazepoxide clearance than did controls. The inhibitory effect of cimetidine on chlordiazepoxide clearance was less in cirrhotics than in controls (p less than 0.05). In all subjects, there was excellent correlation between initial clearance and magnitude of depression in clearance after cimetidine, i.e., the larger the initial clearance, the larger the change (r = 0.97, p less than 0.0001). Forty-eight hours after stopping cimetidine, chlordiazepoxide clearance returned to baseline in cirrhotics and controls. Our data demonstrate that cimetidine and cirrhosis may act additively to impair drug metabolism. This effect of cimetidine on chlordiazepoxide clearance is smaller in cirrhotics than in controls, but, because of impaired initial drug elimination in cirrhosis, it may result in adverse clinical effects.
A series of abdominal radiographs were taken in eight normal volunteers after the ingestion of sodium tyropanoate (Bilopaque). These showed nonabsorbed sodium tyropanoate to have a granular appearance, while the conjugated form had a smooth homogeneous appearance. The appearance of conjugated sodium tyropanoate in the bowel has the same diagnostic significance as conjugated iopanoic acid in the presence of a nonvisualized gallbladder. It indicates that the contrast material has passed through the hepatic ductal system and that there has been an opportunity for the gallbladder to opacify.