Pancreatic extracts in the treatment of pancreatic exocrine insufficiency

In vitro comparative study of three pancreatic enzyme preparations: dissolution profiles, active enzyme release and acid stability

BACKGROUND

Various pancreatic enzyme preparations are used for the treatment of pancreatic insufficiency but their bioequivalence is often unknown.

AIM

To determine in vitro the pH-dependent release and acid resistance of enzymes from three commercially available pancreatin capsules, two containing enteric-coated (Creon 25000; Eurobiol 25000) and one uncoated (Eurobiol 12500) microspheres.

METHODS

Dissolution experiments were performed at pH values ranging from 4.0 to 5.8. Lipase, chymotrypsin and amylase activities were measured in the solution as a function of time.

RESULTS

Eurobiol 25000 started to release its enzymes significantly at pH 5.0 (t(1/2) = 71 min), whereas the enzymes from Creon 25000 were only released at higher pH value (5.4; t(1/2) = 49.2 min). Unlike chymotrypsin, lipase and amylase were highly sensitive to acidic conditions at the lowest pH values tested. Both enzymes were also found to be sensitive to proteolytic inactivation at the highest pH values tested. Overall, Eurobiol 25000 released higher amounts of active amylase and lipase than Creon 25000 at the pH values usually found in duodenal contents. The uncoated Eurobiol 12500 preparation was, however, the only one that could immediately release rather high levels of active chymotrypsin and lipase at low pH (4.5).

CONCLUSION

These findings suggest that pH-sensitive enteric-coated pancreatin products containing similar amounts of enzymes might not be bioequivalent depending on the pH of duodenal contents.

Stability of porcine and microbial lipases to conditions that approximate the proventriculus of young birds

In vitro experiments were conducted to characterize the activity and the stability of lipase from animal (crude porcine, CPL; lyophilized porcine, LPL), fungal (Rhizopus arrhizus, RAL; Aspergillus niger, ANL), and bacterial (two Pseudomonas spp., PL1, PL2; and Chromobacterium viscosum, CVL) sources when exposed to conditions associated with the glandular stomach. Activity was measured at pH 3 to 8, 40 C and then monitored in response to temperature (40 C), time of exposure (0 and 30 min), pH (3 and 7), and pepsin level (5, 50, and 500 U/mL). All lipases except ANL and CVL had maximum activity at pH 7 to 8. The optimal pH for ANL and CVL were 5 and 6 to 8, respectively. Exposure of lipases to 40 C and pH 7 for 30 min reduced the activity of all lipases except ANL. In contrast, 40 C increased ANL activity 2.5-fold. Although activity of all lipases was reduced by exposure to pH 3, it was nearly eliminated for CPL and LPL. Pepsin concentration had only minor effects on lipase activity and then only at high concentration. The results demonstrate that bacterial lipases (PL1, PL2, and CVL) and ANL are more stable under conditions that approximate the glandular stomach and may explain why dietary porcine lipase has been ineffective in preventing fat malabsorption in previous in vivo studies.

Enzyme substitution in pancreatic disease: is colipase activity sufficient?

The aim of the present study was to determine colipase activity in various pancreatic enzyme tablets to ascertain whether these contained sufficient amounts of colipase to activate lipase during fat digestion. Colipase activity in all preparations tested exceeded that of lipase activity by a factor of 1.4-1.9 on a molar activity basis. Since optimal activity of lipase is obtained with colipase being present in a colipase to lipase molar activity ratio of 1.0, it is concluded that these preparations contain a sufficient amount of colipase to activate lipase.

Volume and enzyme kinetics of human pancreatic secretion after endogenous stimulation with the Lundh test meal

The present study was undertaken to investigate the volume and enzyme kinetics of human pancreatic secretion, after endogenous stimulation with a Lundh test meal, and evaluate the most reliable enzyme and collection period. The prestimulatory volume rates did not differentiate normal from pathologic pancreatic function. After ingestion of the test meal, the immediate increase in volume secretion was identical in healthy subjects and patients with pancreatic insufficiency. The latter showed a drastic reduction of prestimulatory and postprandial enzyme secretion. Cimetidine taken orally 12 and 2 h before the test meal study had no effect on volume and enzyme secretion and endogenous CCK release. Especially in severe pancreatic insufficiency, this modification simplified the performance of the Lundh test. The estimation of lipase and trypsin gave a significant correlation between Lundh test and secretin-cerulein test. The endogenous stimulation by Lundh test meal is a reliable test for routine diagnostic and scientific purposes.

Laboratory diagnosis of malassimilation

In many instances, the cause for malassimilation can be determined with ease, but finding the cause sometimes can be elusive and require the use of sophisticated laboratory techniques not available to the general veterinary practitioner. In either case, the clinician, whether generalist or specialist, must make an informed decision based on the results of many different testing modalities, and not only on the results of the laboratory tests described here. A flow chart is provided to assist the diagnostician in selecting and applying the more clinically oriented laboratory tests useful in dealing with a patient with chronic diarrhea and weight loss.

Exocrine pancreatic substitution: facts and controversies

The effect on intraluminal postprandial concentrations of different pancreatic enzymes and on fat absorption were studied in 35 patients with advanced chronic pancreatitis with pancreatic insufficiency. Different regimes were studied: commercial Pankreatin (III) alone or in combination with Cimetidine, Pancrease, dispensed in microspheres, and commercial Pankreatin III compared to an equivalent uncoated preparation (Pankreatin I). Pankreatin induced significant increase in the intestinal concentration of amylase, lipase, and trypsin. Pretreatment with Cimetidine did not increase the enzyme concentrations further. The amount of enzymes in Pancrease capsules are rather small, no effect on concentrations of enzymes could be detected but treatment with Pancrease decreased significantly the fat excretion in faeces. The uncoated Pankreatin I induced a significantly higher increase in enzyme concentrations in the intestine compared to Pankreatin III but the overall effect tested on faecal fat excretion was identical with the two preparations. The results indicate that the estimation of concentration of enzyme at one level of the small intestine without and with enzyme substitution not necessarily gives information on the therapeutical effect of the enzymes.

Pancreatic enzyme replacement: the effect of antacids or cimetidine

The effect of the addition of sodium bicarbonate, aluminum hydroxide, magnesium hydroxide, calcium carbonate, or cimetidine to supplemental pancreatic enzyme therapy was investigated in patients with severe exocrine pancreatic insufficiency. Steatorrhea was reduced with the administration of three enzyme tablets with meals (73 vs 29 g/24 hr). The coadministration of enzyme tablets with either sodium bicarbonate (16.6 g/24 hr, P = 0.08), or aluminum hydroxide (18.4 g/24 hr, P = 0.029) yielded a greater reduction in steatorrhea than enzymes alone (29 g/24 hr). Neither magnesium-aluminum hydroxide (36.3 g/24 hr, P = 0.22), nor calcium carbonate (39.0 g/24 hr, P = 0.029), improved efficacy of enzyme therapy and, in fact, tended to enhance steatorrhea. With the administration of cimetidine there was no significant effect on steatorrhea compared to enzymes alone (32.1 vs 29 g/24 hr, P greater than 0.3). Intraduodenal lipase activity following test meals was found to be a poor predictor of the effectiveness of antacid therapy in improving the efficacy of supplemental enzymes.

Clinical effectiveness of a pancreatic enzyme supplement

In 23 adult patients with pancreatic insufficiency, we evaluated the efficacy of a pancreatic enzyme delivered as pH-sensitive enteric-coated pancreatic lipase microspheres, and compared it with placebo and other available enzyme supplements. In a short-term study, fecal fat was 23.5 +/- 7 g/day with the microspheres, compared with 29.9 +/- 8 with other supplements, providing fat utilization of 76 +/- 7% versus 63 +/- 10% (p less than 0.05). Microspheres reduced daily stool frequency to 1.9 movements from 4.3 on other enzymes (p less than 0.01). These results were obtained with an average intake of 10 microsphere capsules/day. In a year-long study of 22 patients, an average weight gain of 4.0 +/- 1.1 kg was observed associated with return of near-normal social and work life-style in previously housebound patients.

Effect of cimetidine and sodium bicarbonate on pancreatic replacement therapy in cystic fibrosis

Fifteen patients with cystic fibrosis and pancreatic insufficiency were studied during four randomised seven day treatment periods in which they received only pancreatic supplement (Pancrelipase, 27 capsules per day) or supplement plus cimetidine (20 mg/kg body weight/24 h) or sodium bicarbonate (15 g/m2/24 h) alone or in combination. Dietary intake was not fixed but was restricted to foods of known fat and nitrogen content from which daily intakes could be computed. Faecal fat and nitrogen were calculated as g/24 h and percentage of intake. Addition of either cimetidine or bicarbonate resulted in significant improvement in fat and nitrogen excretion, which was not greater with the combination of both drugs. Cimetidine and sodium bicarbonate in these doses are therefore sufficient to produce maximal improvement in digestive activity of pancreatic supplements. Fat excretion per gram of intake fell with cimetidine and bicarbonate from 12 times the normal level, to normal, in patients consuming less than 120 g fat daily. Above this intake the dose of pancreatic supplement appeared to be inadequate. Faecal nitrogen excretion increased with nitrogen intake in all four periods, but, in contrast with fat excretion, the response to cimetidine and bicarbonate was not affected by the level of intake. Dietary intake appears to be a significant factor in determining the faecal output of fat and nitrogen in patients with pancreatic insufficiency and should be considered when determining the optimum amount of pancreatic supplementation.

Intestinal concentrations of pancreatic enzymes following pancreatic replacement therapy

The activities of amylase, lipase, phospholipase, and trypsin in four commercially available preparations of pancreatin with different galenic and adjunctive protective properties were estimated in vitro, using human small-intestinal juice as the incubation medium. These preparations were administered to healthy subjects and to patients with severe pancreatic insufficiency, and their ability to increase the intestinal concentrations of pancreatic enzymes was evaluated. The relations between in vitro and in vivo activities were also studied. In vitro testing showed that the preparations contained high but varying activities of enzymes, with the greatest variations in lipase and trypsin. Pancreatin in the form of tablets, with or without protective measures against acid, did not cause any apparent increase in the activities of pancreatic enzymes in the upper part of the gut in patients with pancreatic insufficiency. Granulated pancreatin, on the other hand, brought about an increase in the activities of amylase, phospholipase, lipase, and trypsin. Relatively higher activities of the enzymes in granulated form reached the small intestine as compared with those of the tablets.

Comparative effects of antacids, cimetidine and enteric coating on the therapeutic response to oral enzymes in severe pancreatic insufficiency

To provide a rational basis for pancreatic enzyme replacement therapy, we evaluated, in six patients with advanced pancreatic insufficiency, the effects of various treatment regimens on fecal fat and nitrogen balance and on duodenal recovery of ingested pancreatic enzymes after a solid test meal. The combination of cimetidine (an H2-receptor antagonist) and pancreatin, each given by mouth, produced significantly higher postprandial duodenal recoveries and concentrations of trypsin and lipase (P less than 0.05). Steatorrhea was reduced in all patients and abolished in four of the six. In the dosages used, neither enteric-coated enzymes nor supplemental neutralizing antacids were more effective than pancreatin alone in decreasing steatorrhea or improving duodenal enzyme delivery. Cimetidine may be a useful adjunct to oral pancreatic extract therapy in some patients with severe pancreatic insufficiency who fail to respond to pancreatic enzyme replacement alone.

Enzymic activities of commercial preparations of pancreatic enzymes

The enzymic activities of 20 commercial pancreatic extracts have been measured by standard (F.I.P.) methods of assay and the activities have been compared with a standard preparation of pancreatin supplied by the British Pharmacopoeia Commission. A wide range of enzymic activities was found. The tabulated cost per unit of enzymic activities provides a guide to one aspect of the potential therapeutic efficacy of pancreatic extracts in the treatment of pancreatic exocrine insufficiency.

Fate of orally ingested enzymes in pancreatic insufficiency. Comparison of two dosage schedules

To assess the fate and efficacy of orally ingested enzymes in pancreatic insufficiency, we administered pancreatin to six patients by two schedules--eight tablets with a standard meal or two tablets hourly--and in six normal controls, quantified duodenal enzyme activity and related inactiviation of ingested enzymes to gastric and duodenal pH; in the six patients we measured malabsorption by fecal balance studies. Postprandially, gastric pH was similar in health and pancreatic insufficiency, and below 4 after 40 minutes. Duodenal pH in pancreatic insufficiency declined to approximately 4 beyond 100 minutes--lower than in health (P less than 0.05). Approximately 22 per cent and 8 per cent of trypsin and lipase activity ingested with either schedule was delivered to the ligament of Treitz. Prandial was as effective as hourly administration in decreasing steatorrhea and perhaps more effective in abolishing azotorrhea, and since it is also more convenient, we recommend it.

Inhibition of gastric secretion in treatment of pancreatic insufficiency

The content of pancreatic enzymes in the duodenum was studied in two patients with pancreatic achylia after a standard meal supplemented with commercial pancreatic extract. Gastric transit of the enzymes, with appearance of near-normal amounts in the duodenal contents, occurred only after inhibition of gastric secretion and buffering of residual gastric acid with antacids. Gastric inhibition and neutralisation of acid are therefore necessary for the satisfactory treatment of patients with pancreatic exocrine insufficiency but normal gastric function.

Studies on intestinal malabsorption in chronic pancreatitis

Pancreozymin-secretin test (PS test) and intestinal absorption tests were performed in 21 patients with chronic calcific pancreatitis and 32 patients with chronic noncalcific pancreatitis to evaluate exocrine functions of the pancreas. And the following results were confirmed. (1) Fecal fat excretion increased in 33% of chronic pancreatitis (47% of calcific pancreatitis and 25% of noncalcific pancreatitis). Serum carotene leves showed significantly low levels in 44% of chronic pancreatitis (67% of calcific pancreatitis and 27% of noncalcific pancreatitis). (2) D-xylose tolerance test was abnormally low in only 6% of chronic pancreatitis, but Schilling test was evaluated abnormally low in 29% of chronic pancreatitis (50% of calcific pancreatitis and 11% of noncalcific pancreatitis). (3) Fecal fat excretion increased in cases of severe exocrine insufficiency of the pancreas with decreased amylase output and decreased maximum bicarbonate concentration in PS test. (4) Correlation of fecal fat excretion to maximum bicarbonate concentration was statistically significant, but those to amylase output or volume of pancreatic juice were not significant. (5) Antacid drugs combined with pancreatic extracts seems to be indispensable in the treatment of chronic pancreatitis as far as malabsorption in chronic pancreatitis is concerned.