Rajendra P. Sarva

Comparative efficacy and side effects of ursodeoxycholic and chenodeoxycholic acids in dissolving gallstones. A double-blind controlled study.

In a double-blind controlled study of ursodeoxycholic acid (400 and 800 mg/day) and chenodeoxycholic acid (375 and 750 mg/day), in comparison with placebo, ursodeoxycholic acid was significantly more effective than chenodeoxycholic acid in dissolving gallstones after 12 mo of treatment. Although there continued to be better dissolution during ursodeoxycholic acid treatment (dissolution complete in 30% and partial in another 30% of the patients) than during chenodeoxycholic acid treatment (dissolution complete in 7% and partial in 40%) at 24 mo, this difference between the treatment groups was no longer statistically significant. The incidence of floating stones was significantly higher in the patients who dissolved their stones than in those who did not (p less than 0.001). The three failures of dissolution of floating stones during bile acid treatment were associated with chenodeoxycholic acid therapy--two of them with the 750-mg and the third with the 375-mg doses. Gallstone dissolution with ursodeoxycholic acid occurred in spite of a rise in biliary cholesterol saturation, which was consistent with a nonmicellar mechanism of cholelitholysis. Furthermore, more than threefold serum elevations of L-alanine aminotransferase were observed only during chenodeoxycholic acid therapy. They occurred in 2 patients treated with 375 and 750 mg/day, respectively. The enzyme levels normalized after discontinuation of chenodeoxycholic acid and have remained normal for 13 and 8 mo, respectively, after the institution of treatment with 800 mg/day of ursodeoxycholic acid. There was no correlation between the liver tests and biliary levels of lithocholic acid. Of all the symptoms studied, only constipation showed changes that approached statistical significance (p = 0.0681). There was a significant improvement of constipation in the combined chenodeoxycholic acid groups when they were compared with the combined ursodeoxycholic acid groups. The total bile acid pool expanded significantly in both the chenodeoxycholic acid and in the 800-mg ursodeoxycholic acid treatment groups. The marked increases of biliary ursodeoxycholic acid and chenodeoxycholic acid, respectively, indicated compliance with the treatment in all but 1 bile acid-treated patient. Neither serum triglycerides nor serum cholesterol showed significant changes in any of the treatment groups. The study shows that ursodeoxycholic acid dissolves gallstones faster and with fewer side effects than chenodeoxycholic acid. The results of the study are also consistent with the view that ursodeoxycholic acid is cholelitholytic at a lower dose than is chenodeoxycholic acid.

Impairment of gallbladder emptying in diabetes mellitus.

Individuals with diabetes mellitus are reported to have a twofold to threefold increase in the incidence of cholesterol gallstones. A frequently cited but unproven pathophysiologic mechanism for this phenomenon is reduced gallbladder muscle function, which results in stasis and allows for cholesterol gallstone crystal formation and gallstone growth. To date, gallbladder motor function has not been investigated in a well-characterized diabetic population. Therefore, using radionuclide cholescintigraphy, gallbladder filling and subsequent emptying produced in response to an infusion of the octapeptide of cholecystokinin in 30 diabetic patients and 20 control individuals were studied. No difference in any parameter used to assess gallbladder filling was demonstrated in the diabetics when compared with controls. In contrast, gallbladder emptying induced with cholecystokinin-octapeptide (20 ng/kg body wt . h) was reduced in diabetics compared with controls (55% +/- 5% vs. 74% +/- 4%, p less than 0.01). The peak emptying rate in the diabetics was also decreased (5.0% +/- 0.5% per minute) compared with the controls (7.0% +/- 0.6% per minute, p less than 0.02). The observed decreased gallbladder emptying found in diabetics was not related to obesity, type of diabetes, diabetic control, or presence or absence of peripheral neuropathy. The most severe impairment of gallbladder emptying occurred, however, in diabetics with an associated autonomic neuropathy. This subgroup demonstrated a significant reduction in the percentage of gallbladder emptying (40% +/- 8% vs. 62% +/- 5%, p less than 0.04) and the peak ejection rate (3.5% +/- 0.5% per minute vs. 5.6% +/- 0.6%, p less than 0.02) compared with the diabetics without autonomic neuropathy.

Comparative formation of lithocholic acid from chenodeoxycholic and ursodeoxycholic acids in the colon.

The comparative rate of formation of lithocholic acid from chenodeoxycholic acid and its 7 beta epimer, ursodeoxycholic acid, was studied in human subjects and in a rhesus monkey. [24-14C]Chenodeoxycholic acid and [24-14C]ursodeoxycholic acid were incubated in vitro, under anaerobic conditions, in fecal samples from 7 control and 7 asymptomatic gallstone subjects. The incubations were carried out for 0, 0.5, 1, 4, and 12 h. In addition, the labeled precursors were instilled into the colon of 4 asymptomatic gallstone patients and a rhesus monkey in which a bile duct fistula had been created. Radioactive metabolites were analyzed by thin-layer chromatography in the in vitro fecal incubates and in the in vivo colonic aspirates, stool, and bile. The biotransformation of the unlabeled material was analyzed by gas-liquid chromatography in the in vitro incubates and in the in vivo fecal samples of the rhesus monkey. There was no statistical difference between chenodeoxycholic and ursodeoxycholic acids in their rate of biotransformation to lithocholic acid, when the total group of 14 subjects was compared. However, among these 14, a subgroup of 4 subjects (2 controls and 2 with gallstones) was identified in whom the rate of degradation to lithocholic acid was significantly faster for chenodeoxycholic than for ursodeoxycholic acid. Increases in the concentrations of the precursors led to a decrease in the rate, but not a change in the comparative pattern of lithocholic acid formation. At the lower concentrations, the conversion of both bile acids to lithocholic acid was almost complete after 12 h. In the in vivo studies, the formation of lithocholic acid from chenodeoxycholic and ursodeoxycholic acids was comparable both in the 4 human subjects and in the rhesus monkey. The results of this study indicate that, in most cases, the risk of liver damage from lithocholic acid formation should be similar for both epimers. However, there appears to be a small population in which this risk could be higher during chenodeoxycholic acid than during ursodeoxycholic acid treatment due to a more rapid formation of lithocholic acid.

Study of the sensitivity and specificity of computerized tomography in the detection of calcified gallstones which appear radiolucent by conventional roentgenography

Radiolucent gallstones frequently contain significant calcium deposits. Their detection is important in the evaluation of patients for medical gallstone dissolution treatment. The sensitivity and specificity of computerized tomography (CT) in detecting calcium was studied in 20 patients with radiolucent and in 3 with radiopaque gallstones. Although the sensitivity of the CT scan was somewhat higher than that of conventional radiography — 46% versus 23%, respectively, for a calcium content of at least 4% — the CT scan was negative in 4 out of 6 patients in whom the percentage of calcium in the gallstones ranged between 10 and 100. The CT scan was specific: there were no false positive results. The results of the CT scan were not related to the amount or type of calcium salt present. The study shows that the presently used CT scan of the gallbladder is not sensitive enough to select gallstone patients for medical dissolution treatment.

Effects of jejunoileal bypass on the enterohepatic circulation of bile acids, bacterial flora in the upper small intestine, and absorption of vitamin B12

Eleven morbidly obese patients were studied before and at various time intervals after jejunoileal bypass (JIB). Bile acid deconjugation was assessed with the bile acid breath test and bile acid absorption by analyzing the fecal excretion of both radioactively labeled and unlabeled bile acids. In addition, aerobic and anaerobic cultures of upper small intestinal aspirates, the Schilling vitamin B12 absorption test, and fecal fat analysis were performed. All patients developed marked diarrhea and steatorrhea after JIB. The bile acid breath test was positive in all 11 patients after JIB. In 7 of the 11 patients, this test was already slightly positive before JIB. In every instance, however, the bile acid breath test became significantly more abnormal after the bypass operation. The fecal excretion of labeled bile acids increased significantly. However, the increase in the quantitative excretion of the bile acids did not reach statistical significance. The concentrations of bile acids in fecal water were considerably below the levels required to induce diarrhea. This was mainly the result of a low fecal pH and consequent low aqueous solubility. Jejunoileal bypass effected a major shift in fecal bile acids from the secondary bile acids, lithocholic acid and deoxycholic acid, to the respective primary compounds, chenodeoxycholic acid and cholic acid. There were no significant changes in the small bowel bacteriologic findings after JIB. In 5 out of the 9 patients in whom bacteriologic studies were performed, the cultures were positive before the operation. The Schilling vitamin B12 absorption test showed in all patients a significant drop in the 24-hour urinary 57Co excretion rate after JIB.(ABSTRACT TRUNCATED AT 250 WORDS)

Thiazide-induced hypercholesterolemia: Sex differences

Thiazide diuretics are used commonly to treat hypertension. Unfortunately, they also are known to elevate serum cholesterol levels. Because serum lipid fraction levels differ between the sexes, possible sex-related differences in thiazide-induced changes in serum total cholesterol (TC), triglycerides (TG) and high density lipoprotein cholesterol (HDL-C) levels were examined. Four groups of male and female hamsters were treated for a minimum of 3 months with hydrochlorothiazide (HCTZ) at zero, 1, 2 or 4 mg/kg/day. At zero dose, there was no difference in TG levels between the sexes; however, females had significantly higher TG concentrations than did males at 1, 2 and 4 mg HCTZ (all p less than 0.05). Females demonstrate a significant dose response with HCL-C levels increasing with increasing doses of HCTZ, (r = 0.983; p less than 0.02); in contrast males had a similar increase in HDL-C at all dose levels (all p less than 0.05) thus there was no demonstrable dose response (r = 0.539). Total cholesterol concentrations were significantly higher in the females than in males (p less than 0.05) at all 3 dose levels as well as at zero dose. Further, the females demonstrated a direct dose response in TC levels (r = 0.986; p less than 0.02) while the males showed no such dose response (r = 0.824; p less than 0.01). Based on these findings we conclude that: 1) HCTZ increases TG, TC and HDL-C levels in both male and female hamsters; 2) TC levels are higher in females than in males regardless of HCTZ dose; 3) only females show a dose-dependent increase in HCL-C and TC in response to HCTZ. These sex-related changes in lipid fractions occurring with HCTZ treatment, if they occur in humans, may contribute to sex-related differences in rates and severity of atherosclerosis in HCTZ-treated populations.