Pancreatic enzyme replacement: the effect of antacids or cimetidine

Study of the gastrointestinal bioavailability of a pancreatic extract product (Zenpep) in chronic pancreatitis patients with exocrine pancreatic insufficiency

INTRODUCTION

The Food and Drug Administration in 2006 required that all pancreatic enzyme products demonstrate bioavailability of lipase, amylase, and protease in the proximal small intestine.

METHODS

In this phase I open-label, randomized, crossover trial, 17 adult chronic pancreatitis (CP) patients with severe exocrine pancreatic insufficiency (EPI) underwent two separate gastroduodenal perfusion procedures (Dreiling tube suctioning and [¹⁴C]-PEG instillation by an attached Dobhoff tube in the duodenal bulb). Patients received Ensure Plus® alone and Ensure Plus with Zenpep (75,000 USP lipase units) in random order. The bioavailability of Zenpep was estimated by comparing the recovery of lipase, amylase, chymotrypsin activity in two treatment conditions. ¹⁴C-PEG was used to correct duodenal aspirates volume. The primary efficacy endpoint was lipase delivery in the duodenum after Zenpep administration under fed conditions. Secondary efficacy endpoints included chymotrypsin and amylase delivery, serum CCK levels, and measuring duodenal and gastric pH.

RESULTS

Zenpep administration with a test meal was associated with significant increase in duodenal aspiration of lipase (p = 0.046), chymotrypsin (p = 0.008), and amylase (p = 0.001), compared to the test meal alone, indicating release of enzymes to the duodenum. Lipase delivery was higher in the pH subpopulation (the efficacy population with acid hypersecretors excluded) (p = 0.01). Recovery of [¹⁴C]-PEG was 61%. Zenpep was generally well tolerated. All adverse events were mild and transient.

CONCLUSIONS

In CP patients with severe EPI, lipase, chymotrypsin and amylase were released rapidly into the duodenum after ingestion of Zenpep plus meal compared to meals alone. Results also reflected the known pH threshold for enzyme release from enteric coated products.

Rational Use of Pancreatic Enzymes for Pancreatic Insufficiency and Pancreatic Pain

We describe the rational use of enteric coated and unprotected replacement pancreatic enzymes for treatment of malabsorption due to pancreatic insufficiency and for pancreatic pain. Enteric coated formulations mix poorly with food allowing separation of enzymes and nutrients when emptying from the stomach. The site of dissolution of the enteric coating in the intestine is also unpredictable and enzymes may not be released until the distal intestine. Together, these barriers result in the lack of dose-response such that the strategy of increasing the dosage following a suboptimal effect is often ineffective. The ability to maintain the intragastric pH ≥4 with the combination of proton pump inhibitors and antacids suggests that it should be possible to reliably obtain a good response with uncoated enzymes. We also discuss the recognition, treatment and prevention of nutritional deficiencies associated with pancreatic insufficiency and recommend a test and treat strategy to identify and resolve nutritional deficits. Finally, we focus on mechanisms causing pain that may be amenable to therapy with pancreatic enzymes. Pain due to malabsorbed digestive contents can be prevented by successful therapy of malabsorption. Feedback inhibition of endogenous pancreatic secretion can prevent pain associated with pancreatic secretion but requires use of non-enteric coated formulations.

The Pancreatic Duct Ligated (Mini)pig as a Model for Pancreatic Exocrine Insufficiency in Man

Modern therapy of pancreatic exocrine insufficiency (PEI) using pancreatic enzyme replacement therapy (PERT) has largely been very effective and has greatly helped in improving the nutritional status of patients with PEI and in increasing the life expectancy in cystic fibrosis. It is believed that the use of predictable large animal models could play an important role in assessing and developing new therapies. This article reviews the pancreatic duct ligated (adult) minipig as a chronic model of total PEI, with a detailed look at the influence of PEI and response to PERT on prececal compared to fecal digestibility, to directly investigate effects on protein and starch digestion and absorption. In addition, the piglet with PEI is reviewed as a model for PEI in young patients with the aim of further improving the therapy and nutritional status of young patients with cystic fibrosis.

Pancreatic enzyme replacement therapy for pancreatic exocrine insufficiency in the 21st century

Restitution of normal fat absorption in exocrine pancreatic insufficiency remains an elusive goal. Although many patients achieve satisfactory clinical results with enzyme therapy, few experience normalization of fat absorption, and many, if not most, will require individualized therapy. Increasing the quantity of lipase administered rarely eliminates steatorrhea but increases the cost of therapy. Enteric coated enzyme microbead formulations tend to separate from nutrients in the stomach precluding coordinated emptying of enzymes and nutrients. Unprotected enzymes mix well and empty with nutrients but are inactivated at pH 4 or below. We describe approaches for improving the results of enzyme therapy including changing to, or adding, a different product, adding non-enteric coated enzymes, (e.g., giving unprotected enzymes at the start of the meal and acid-protected formulations later), use of antisecretory drugs and/or antacids, and changing the timing of enzyme administration. Because considerable lipid is emptied in the first postprandial hour, it is prudent to start therapy with enteric coated microbead prior to the meal so that some enzymes are available during that first hour. Patients with hyperacidity may benefit from adjuvant antisecretory therapy to reduce the duodenal acid load and possibly also sodium bicarbonate to prevent duodenal acidity. Comparative studies of clinical effectiveness of different formulations as well as the characteristics of dispersion, emptying, and dissolution of enteric-coated microspheres of different diameter and density are needed; many such studies have been completed but not yet made public. We discuss the history of pancreatic enzyme therapy and describe current use of modern preparations, approaches to overcoming unsatisfactory clinical responses, as well as studies needed to be able to provide reliably effective therapy.

Retrospective analysis to investigate the effect of concomitant use of gastric acid-suppressing drugs on the efficacy and safety of pancrelipase/pancreatin (CREON®) in patients with pancreatic exocrine insufficiency

OBJECTIVES

This study aimed to determine whether the efficacy of pancrelipase/pancreatin (CREON®) may be affected by the concomitant use of proton pump inhibitors (PPIs)/histamine-2 receptor antagonists (H2RAs).

METHODS

An analysis of integrated data from all clinical trials of pancrelipase/pancreatin supported by Abbott (34 trials, 1142 unique subjects) was conducted. All trials included patients with pancreatic exocrine insufficiency, and most cases were associated with cystic fibrosis, chronic pancreatitis, or pancreatic surgery. Study designs included single and double blind, open label, parallel group, and crossover, and most were randomized. The primary end point for this analysis was on-treatment coefficient of fat absorption (CFA) according to concomitant PPI/H2RA use (yes/no).

RESULTS

There were no meaningful differences in mean CFA values at the end of pancrelipase/pancreatin treatment by concomitant PPI/H2RA use: yes (n = 254), 82.7% versus no (n = 449), 84.2%. No meaningful differences were observed when the same analysis was carried out by disease type (cystic fibrosis, chronic pancreatitis, and pancreatic surgery).

CONCLUSIONS

This analysis of data from clinical trials enrolling patients with pancreatic exocrine insufficiency suggests that the efficacy of pancrelipase/pancreatin is not affected by concomitant PPI/H2RA use, as determined by end-of-treatment CFA values, and supports the treatment guidelines' recommendation that acid suppression is not routinely required with pancreatic enzyme replacement therapy.

Delayed release pancrelipase for treatment of pancreatic exocrine insufficiency associated with chronic pancreatitis

Pancreatic enzyme supplements (PES) are used in chronic pancreatitis (CP) for correction of pancreatic exocrine insufficiency (PEI) as well as pain and malnutrition. The use of porcine pancreatic enzymes for the correction of exocrine insufficiency is governed by the pathophysiology of the disease as well as pharmacologic properties of PES. Variability in bioequivalence of PES has been noted on in vitro and in vivo testing and has been attributed to the differences in enteric coating and the degree of micro-encapsulation. As a step towards standardizing pancreatic enzyme preparations, the Food and Drug Administration now requires the manufacturers of PES to obtain approval of marketed formulations by April 2010. In patients with treatment failure, apart from evaluating drug and dietary interactions and compliance, physicians should keep in mind that patients may benefit from switching to a different formulation. The choice of PES (enteric coated versus non-enteric coated) and the need for acid suppression should be individualized. There is no current standard test for evaluating adequacy of therapy in CP patients and studies have shown that optimization of therapy based on symptoms may be inadequate. Goals of therapy based on overall patient presentation and specific laboratory tests rather than mere correction of steatorrhea are needed.

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.

Enteric-coated pancreatic enzyme with bicarbonate is equal to standard enteric-coated enzyme in treating malabsorption in cystic fibrosis

OBJECTIVES

To compare the efficacy of an enteric-coated buffered pancreatic enzyme (EC buffered PE) containing 1.5 mEq of bicarbonate per capsule with a conventional enteric-coated enzyme (EC-PE) capsule in cystic fibrosis patients with signs or symptoms of moderate to severe malabsorption.

METHODS

In a double-blind crossover study, subjects were randomly assigned to two consecutive, 2-week phases using an EC buffered PE product and conventional EC-PE product. Seventy-two hour stool collections from each phase were analyzed for energy, fat, and nitrogen content and expressed as percent of estimated intake.

RESULTS

Twenty-one patients with cystic fibrosis and pancreatic insufficiency (14 female, mean age 20.6 +/- 11.5 years, range 8.8-41.9) completed the study. There was no significant difference in percent malabsorption of energy (19.4% vs. 19.0%), fat (20.7% vs. 20.2%), or nitrogen (10.4% vs. 10.7%) between the EC buffered PE product and the conventional EC-PE product. However, patients taking the EC buffered PE product received less enzyme based on actual enzyme activity measured in vitro (3,468 +/- 1,434 U lipase/g fat vs. 3,978 +/- 1,474 U lipase/g fat, P < 0.02).

CONCLUSIONS

In the doses used, nutrient absorption of patients taking EC buffered PE preparation offers no advantage over a conventional EC-PE preparation.

Diagnosis and treatment of intestinal malabsorption in cystic fibrosis

Intestinal malabsorption is severe and of early onset in virtually all people who have cystic fibrosis. The main cause is deficiency of pancreatic enzymes. Bicarbonate deficiency, abnormal bile salts, mucosal transport problems, motility differences, and anatomical structural changes are other contributory factors. Effective treatment should allow a normal to high-fat diet to be taken, control symptoms, correct malabsorption, and achieve a normal nutritional state and growth. Appropriate pancreatic enzyme replacement therapy will achieve normal or near-normal absorption in most people with cystic fibrosis. Early identification and treatment of intestinal malabsorption is critical to achieving optimal nutritional status. The occurrence of fibrosing colonopathy in a few patients on very high doses of those enzymes which have the copolymer Eudragit L30 D55 in their covering resulted in guidelines in the UK to avoid doses equivalent to more than 10,000 IU lipase per kg per day, and also to avoid preparations containing this copolymer in children and adolescents. For patients not responding to 10,000 IU lipase per kg per day review of adherence to treatment, change of enzyme preparation, variation in time of administration, and reduction in gastric acid may improve absorption. The importance of early investigation to exclude other gastrointestinal disorders as a cause of the patient's symptoms, rather than merely increasing the dose of enzymes, is stressed. With modern pancreatic enzymes in doses up to or only slightly in excess of 10,000 IU lipase per kg per day, adequate control of gastrointestinal symptoms and absorption can be achieved, and a normal nutritional state and growth rate maintained in most people with cystic fibrosis.

Manifestations digestives au cours de la mucoviscidose

The prognosis of cystic fibrosis (CF) is strongly linked to the pulmonary status, nevertheless digestive disorders should be taken into account in order to prevent malnutrition which may increase pulmonary surinfections and speed up the deterioration of the respiratory function. Digestion, gut motility and absorption are the three major functions of the gastrointestinal tract. Functional disorders may involve the whole gut; in addition to pancreatic insufficiency we describe the failure of chloride secretion with dehydration of bowel content. Insufficient knowledge of the pathophysiology stresses the need for further studies to allow development of more rational and effective therapy.

Alcohol-induced pancreatic injury

Alcoholic pancreatitis is a major complication of alcohol abuse. Until recently, it was generally accepted that alcoholic pancreatitis was a chronic disease from the outset. However, evidence is now emerging in support of the 'necrosis-fibrosis' hypothesis that alcoholic pancreatitis begins as an acute process and that repeated episodes of acute injury lead to the changes of chronic pancreatitis (acinar atrophy and fibrosis) resulting in exocrine and endocrine dysfunction. The treatment of acute pancreatitis follows the regimen of bed rest, nasogastric suction, analgesia and intravenous support. The role of additional therapeutic measures such as prophylactic antibiotics, antioxidants and enteral nutrition in severe cases has not yet been precisely defined. The treatment of chronic pancreatitis involves attention to its three cardinal features: pain, maldigestion and diabetes. With respect to the pathogenesis of alcoholic pancreatitis, the focus of research over the past 30 years has shifted from the sphincter of Oddi and ductular abnormalities to the acinar cell itself. It has now been established that the acinar cell is capable of metabolizing alcohol and that direct toxic effects of alcohol and/or its metabolites on acinar cells may predispose the gland to injury in the presence of an appropriate trigger factor. A significant recent development relates to the characterization of pancreatic stellate cells, increasingly implicated in alcoholic pancreatic fibrosis. This chapter summarizes the natural history, clinical features, current trends in treatment as well as recent advances in our understanding of the pathogenesis of alcoholic pancreatitis.

Conservative treatment of chronic pancreatitis

Chronic pancreatitis has been difficult to treat because the origin, pathophysiologic mechanisms and causes of unrelenting pain are so poorly understood. Furthermore, the pharmacologic agents often employed in other diseases with pain appear to be ineffective in many cases. The conservative management of chronic pancreatitis aims at (1) limiting progression and complications of the disease; (2) replacing lost exocrine and endocrine function; and (3) pain control. Thus, life style changes such as cessation of alcohol consumption and tobacco smoking, trials of pancreatic enzymes, treatment of duct obstruction and pseudocysts, and surgical therapies are currently employed. The good news is that the understanding of the underlying pathophysiological mechanisms is now advancing rapidly, and hopefully patient-specific and highly effective therapies will become available in the near future.

Control of malabsorption in cystic fibrosis

Intestinal malabsorption is severe and of early onset in virtually all people who have cystic fibrosis. The main cause is deficiency of pancreatic enzymes, but bicarbonate deficiency, abnormalities of bile salts, mucosal transport and motility, and anatomical structural changes are other contributory factors. Appropriate pancreatic replacement therapy will achieve normal or near normal absorption in many patients. It is important to identify both malabsorption and evidence of a pancreatic lesion in all patients who are to receive pancreatic enzymes. All who have evidence of fat malabsorption are deemed pancreatic insufficient and candidates for enzyme replacement therapy. Effective treatment should allow a normal diet to be taken, control symptoms, correct malabsorption and achieve a normal nutritional state and growth. The occurrence of fibrosing colonopathy in some patients receiving very high doses of those enzymes that have the copolymer Eudragit L30 D55 in their covering has resulted in guidelines in the UK to avoid dosages greater than the equivalent of 10,000 IU lipase/kg/day for all patients and also to avoid preparations containing this copolymer in children and adolescents. For patients not responding to 10,000 IU lipase/kg/day, review of adherence to treatment, change of enzyme preparation, variation of the time of administration and reduction in gastric acid may improve absorption. The importance of excluding other gastrointestinal disorders as a cause of the patient's symptoms and the need for early investigations, rather than merely increasing the dosage of enzymes, is stressed. With modern enzymes, adequate control of gastrointestinal symptoms and absorption can be achieved at dosages of 10,000 IU lipase/kg/day or only slightly more, and a normal nutritional state and growth rate maintained in most patients with cystic fibrosis.

Chronic pancreatitis: complications and management

Chronic pancreatitis is characterized by progressive and irreversible loss of pancreatic exocrine and endocrine function. In the majority of cases, particularly in Western populations, the disease is associated with alcohol abuse. The major complications of chronic pancreatitis include abdominal pain, malabsorption, and diabetes. Of these, pain is the most difficult to treat and is therefore the most frustrating symptom for both the patient and the physician. While analgesics form the cornerstone of pain therapy, a number of other treatment modalities (inhibition of pancreatic secretion, antioxidants, and surgery) have also been described. Unfortunately, the efficacy of these modalities is difficult to assess, principally because of the lack of properly controlled clinical trials. Replacement of pancreatic enzymes (particularly lipase) in the gut is the mainstay of treatment for malabsorption; the recent discovery of a bacterial lipase (with high lipolytic activity and resistance to degradation in gastric and duodenal juice) represents an important advance that may significantly increase the efficacy of enzyme replacement therapy by replacing the easily degradable porcine lipase found in existing enzyme preparations. Diabetes secondary to chronic pancreatitis is difficult to control and its course is often complicated by hypoglycaemic attacks. Therefore, it is essential that caution is exercised when treating this condition with insulin. This paper reviews recent research and prevailing concepts regarding the three major complications of chronic pancreatitis noted above. A comprehensive discussion of current opinion on clinical issues relating to the other known complications of chronic pancreatitis such as pseudocysts, venous thromboses, biliary and duodenal obstruction, biliary cirrhosis, and pancreatic cancer is also presented.

Effect of bacterial or porcine lipase with low- or high-fat diets on nutrient absorption in pancreatic-insufficient dogs

BACKGROUND & AIMS

Treatment of human exocrine pancreatic insufficiency is suboptimal. This study assessed the effects of bacterial lipase, porcine lipase, and diets on carbohydrate, fat, and protein absorption in pancreatic-insufficient dogs.

METHODS

Dogs were given bacterial or porcine lipase and 3 diets: a 48% carbohydrate, 27% fat, and 25% protein standard diet; a high-carbohydrate, low-fat, and low-protein diet; or a low-carbohydrate, high-fat, and high-protein diet (66%/18%/16% and 21%/43%/36% calories).

RESULTS

With the standard diet, coefficient of fat absorption increased dose-dependently with both lipases (P < 0.05), but more fat was absorbed with porcine lipase (P < 0.05); 600, 000 IU of bacterial lipase (240 mg) and 300,000 IU of porcine lipase (18 g) nearly abolished steatorrhea. With 300,000 IU of bacterial lipase or 135,000 IU of porcine lipase, fat absorption was greater with the high-fat and -protein diet (P < 0.05 vs. low-fat and -protein diet). There were no interactions among carbohydrate, fat, and protein absorption.

CONCLUSIONS

Correcting steatorrhea requires 75 times more porcine than bacterial lipase (18 vs. 240 mg). High-fat and high-protein diets optimize fat absorption with both enzymes. High-fat diets with bacterial or porcine lipase should be evaluated in humans with pancreatic steatorrhea.

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.

Effects of high-lipase pancreatin on fecal fat, neutral sterol, bile acid, and short-chain fatty acid excretion in patients with pancreatic insufficiency resulting from chronic pancreatitis

CONCLUSIONS

Steatorrhea was almost completely stopped and malabsorption of neutral sterols and short-chain fatty acids was reduced by treatment of high-lipase pancreatin in Japanese patients with pancreatic insufficiency whose dietary fat consumption is low.

METHODS

Fifteen patients with chronic pancreatitis complicated by steatorrhea who consumed an average of 48 g of dietary fats a day were selected as subjects and given 3 g of high-lipase pancreatin (lipase, 379,800 USP U/g), at each meal (total daily dose is 9 g) for a mean duration of 28.5 d. Fecal output and fecal fat neutral sterol, bile acid, and short-chain fatty acid excretion were determined before and after the course of pancreatin therapy.

RESULTS

Pancreatin administration resulted in significant reductions (P < 0.01) in fecal output (from 243.2 to 149.1 g), excretion of fecal fat, (from 12.3 to 3.9 g), animal sterols (from 816.3 to 604.6 mg), and short-chain fatty acids (from 52.6 to 18.5 mM). In contrast, no marked changes were recorded in fecal excretion of beta-sitosterol (a plant sterol), bile acids, or the hydroxy fatty acid fraction. Fecal fat and short-chain fatty-acid excretion showed strong correlations with fecal output.

Effects of pancreatic digestive enzymes, sodium bicarbonate, and a proton pump inhibitor on steatorrhoea caused by pancreatic diseases

Forty-five patients with pancreatic steatorrhoea (27 with calcified pancreatitis, 13 with non-calcified pancreatitis, two with pancreaticoduodenectomy, one with total pancreatectomy, and two with pancreatic cancer) were divided into four groups and given the following medication for 2 to 4 weeks: 4 to 6 g/day of sodium bicarbonate (group I); 9 g/day of high-lipase pancreatin (lipase, 56,600 U/g, Fédération Internationale Pharmaceutique (FIP); group II); 12 to 24 tablets or 9.0 g of commercial pancreatic enzyme preparations (group III); or 50 mg of omeprazole (group IV). Faecal fat excretion was evaluated before and after drug administration. Faecal fat excretion was reduced by 2.9 g (range, 1.7 to 5.0 g) in group I; 8.8 g (range, 2.9 to 39.9 g) in group II; 10.8 g (range, 2.3 to 21.8 g) in group III; and 4.3 g (range, 3.6 to 5.6 g) in group IV. The pancreatic digestive enzyme preparation was more effective than sodium bicarbonate and agents that raise the pH of the upper small intestine (such as proton-pump inhibitors) in reducing faecal fat excretion. The results indicate that all of the preparations used are effective against mild pancreatic steatorrhoea. If the condition is more advanced, however, a massive dosage of pancreatic digestive enzyme and possibly the combined use of an agent to raise the pH of the upper small intestine are likely to be effective.

Lipolytic activity of bacterial lipase survives better than that of porcine lipase in human gastric and duodenal content

BACKGROUND/AIMS

Treatment of pancreatic steatorrhea with porcine lipase is unsatisfactory because it is rapidly denatured by acidic intraluminal conditions. The aim of this study was to determine if bacterial lipase is resistant to acid denaturation and is active in the presence of bile acids by comparing its stability with that of porcine lipase in gastric and duodenal juice obtained from six patients undergoing a cholecystokinin octapeptide pancreatic function test.

METHODS

After inactivating native lipolytic activity, both juices were altered to simulate fasting and postprandial conditions in normal patients and patients with pancreatic insufficiency. Gastric juice was adjusted to pH 2, 3, 4, or 6, duodenal juice to pH 4 or 6, and bile acid concentrations to 4 or 12 mmol/L. Nutrients were added to one half of the samples. Initial bacterial or porcine lipolytic concentrations were 25 or 250 U/mL. After a 1-hour incubation at 37 degrees C, lipolytic activity was remeasured.

RESULTS

In gastric juice, more bacterial lipolytic activity survived than porcine lipolytic activity at both concentrations in the absence of nutrients and at a concentration of 25 U/mL with nutrients (P < 0.05). In duodenal juice, more bacterial lipolytic activity survived than porcine activity at pH 4 under all test conditions (P < 0.05).

CONCLUSIONS

Bacterial lipolytic activity should survive better within the gastrointestinal lumen than porcine lipolytic activity and be more effective to treat steatorrhea.

Comparative effects of adjuvant cimetidine and omeprazole during pancreatic enzyme replacement therapy

In a double-blind, randomized crossover study, the hypotheses were tested that more powerful inhibition of gastric acid secretion by adjuvant omeprazole further improves the efficacy of pancreatic enzyme replacement therapy compared to adjuvant cimetidine and that excluding the influence of pH-related factors, by virtually complete inhibition of gastric acid secretion with 60 mg omeprazole daily, does not lead to total elimination of steatorrhea. During both adjuvant cimetidine and omeprazole treatment, fecal fat excretion was significantly lower compared to pancreatin monotherapy (P < 0.01). Omeprazole showed a trend towards a more favorable decrease of fecal fat excretion compared to cimetidine but no statistically significant difference. Steatorrhea was almost never abolished, even during 60 mg omeprazole daily. Generally, pH-related factors are considered to explain an inadequate therapeutic response during pancreatic enzyme replacement therapy. However, this study indicates that in vivo other factors also play a significant role.

Nutritional management of acute and chronic pancreatitis

Acute pancreatitis often results in a catabolic state characterized by profound hemodynamic, metabolic, cardiovascular, pulmonary, hematologic, and renal aberrations. Parenteral nutrition and metabolic support are essential if morbidity and mortality are to be minimized. In chronic pancreatitis, nutritional management ranges from fundamental dietary manipulation with or without administration of appropriate digestive enzymes to enteral supplementation with modular chemically defined diets to total parenteral nutrition, depending on the stage, severity, and manifestations of the disease. In prescribing nutrient substrates in both acute and chronic pancreatitis, consideration must be given to their effects on pancreatic enzyme secretion if optimal results are to be achieved.

Non-invasive assessment of intraluminal lipolysis using a 13CO2 breath test

Techniques available for the study of lipase activity in the gut are unsatisfactory. Breath tests measuring labelled carbon dioxide (13CO2) may provide a useful means for this assessment. Six subjects with cystic fibrosis and pancreatic insufficiency and 10 controls received a test meal containing [13C] trioctanoin, and breath 13CO2 was measured using a dual inlet, dual detector isotope ratio mass spectrometer. Comparison of postprandial breath 13CO2 enrichment allowed complete separation between children with pancreatic insufficiency and controls. Administration of one capsule of pancreatic enzyme with the test meal resulted in an increase in 13CO2 production in all six patients, and four capsules produced a further increase in five of the six. Serial fat balance studies on four of the patients while receiving comparable doses of oral enzyme failed to demonstrate a progressive improvement in fat absorption. The [13C]trioctanoin breath test may prove a safe, non-invasive technique not only for the detection of pancreatic insufficiency, but also for the quantitative study of intraluminal lipolysis.

Self-administration of enzyme substitution in the treatment of exocrine pancreatic insufficiency

The effect of self-administration (ad lib) of pancreatic enzyme substitution (Pancrease) in comparison with the dosage recommended by the manufacturer on abdominal symptoms and nutritional variables was studied in 10 patients with chronic pancreatitis. Both dosages were started in randomized order and they were continued for 4 weeks. Before and after each period of administration the patients were studied physically and weighed, and laboratory tests were performed. In addition, the patients kept daily records of pain (score, 0-3), bowel movements, amount of medication needed for maximum relief of symptoms and other remarks, if any. During self-administration, the number of capsules taken increased (5 +/- 1.3 to 11.4 +/- 2.4; p less than 0.001), the frequency of bowel movements decreased (3.6 +/- 1.4 to 1.6 +/- 0.7; p less than 0.05), and the pain was also relieved significantly (2.2 +/- 0.7 to 1.1 +/- 0.7; p less than 0.05) when compared with the regular dosage. Self-administration of the preparation did not have any significant effects on nutritional variables. Dryness of the mouth was the only complaint during self-administration of the drug in 4 of 10 patients. In conclusion, this study in selected patients with chronic pancreatitis indirectly supports the presence of a negative feedback regulation of exocrine pancreatic secretion in man. Thus, it may be beneficial to try self-administration of pancreatic enzyme substitution in selected patients to achieve maximum relief of symptoms in chronic pancreatitis.

Acid resistant lipase as replacement therapy in chronic pancreatic exocrine insufficiency: a study in dogs

Conventional treatment of pancreatic steatorrhoea in man has been unsatisfactory because 90% of the lipase content of therapy is inactivated by acid in the stomach and large doses of replacement treatment are needed to provide adequate supplementation. An acid stable agent (fungal lipase) was investigated in the treatment of pancreatic deficiency steatorrhoea in 11 pancreatectomised dogs maintained on a fixed dietary intake of fat and treated with pancreatin or fungal lipase. Ten grams (60,000 U lipase) of pancreatin was compared with 400mg (4800 U lipase) of fungal lipase administered with each meal against a no treatment group. There was no significant difference in stool bulk and faecal fat excretion between pancreatin and lipase treated animals. Both groups showed a significant reduction in stool bulk and fat excretion when compared with the no treatment group (p less than 0.01). A markedly diminished treatment volume, in the form of fungal lipase, is as effective in controlling steatorrhoea as pancreatin and may prove to be a potentially valuable therapy for patients with pancreatic insufficiency.

Alterations in digestive function caused by pancreatic disease

Pancreatic exocrine secretion is regulated by a complex interaction of meal-stimulated neurohormonal reflexes. Pancreatic enzyme output must be reduced to less than 10 per cent of normal before fat absorption is appreciably impaired, proving that the pancreas secretes a large surplus of enzymes. Surgical therapy does not improve pancreatic exocrine insufficiency, and partial pancreatic resection frequently precipitates steatorrhea in patients with chronic pancreatitis. Therefore, pancreatic resection should be undertaken cautiously in patients who do not yet have clinically evident exocrine insufficiency. In most patients, oral pancreatic enzymes will control diarrhea secondary to steatorrhea. In others, concurrent administration of an H2 blocker is required to reduce gastric acidity and prevent enzyme inactivation in the stomach. Formulations with an acid-resistant coating are also effective in some patients. However, complete normalization of fat absorption with restoration of body weight and nutritional well-being requires careful management of multiple dietary and behavioral factors, as well as long-term follow-up. Unfortunately, this appears to be an elusive goal, as many patients with chronic pancreatitis continue to die of malnutrition.

Pancreatic enzyme replacement therapy. Importance of gastric acid secretion, H2-antagonists, and enteric coating

The relative efficacy of three commercial pancreatic enzyme supplements in improving fat absorption was studied using the [14C]triolein breath test in 12 patients with chronic pancreatitis. Two of the supplements were enteric coated. The one nonenteric coated product was studied twice: with and without ranitidine coadministration. Doses complied with the manufacturers recommendations. Baseline studies included pentagastrin-stimulated gastric acids, 72-hr fecal fat excretion, and [14C]triolein absorption while not on supplementation. Acid outputs were variable (BAO: 0.3-4.1 meq/hr; MAO: 3.5-34.6 meq/hr). Three patients had mild steatorrhea (i.e., less than 10 g/day) and the remaining severe fat malabsorption (56.9 +/- 41.5 g/day). Although fat absorption was significantly improved by all three supplements, the nonenteric coated preparation was most effective (P less than 0.001). However, laboratory analysis demonstrated that lipase content was four times greater, ie, 17,000 IU/4 tablets. Pretreatment with ranitidine failed to further improve the absorption in patients given nonenteric supplements but was effective in those found to have high or normal acid outputs (P less than 0.001). Our results suggest that the recommended dosage of enteric coated preparations is insufficient for adult patients with severe chronic pancreatitis. Secondly, the marked variability of acid secretion in such patients possibly accounts for the variability of results obtained by others on the usefulness of coadministration of antacids and H2 antagonists. Routine measurement of gastric acid secretion status may help optimize the choice and form of pancreatic enzyme supplementation.

Duodenal instillation of pancreatin does not abolish steatorrhea in patients with pancreatic insufficiency

Many believe that intragastric deactivation of lipase accounts for the frequent failure of orally ingested pancreatic enzymes to normalize fat absorption in patients with pancreatic insufficiency. To test this hypothesis, we measured fat absorption from a large test meal in six patients with pancreatic insufficiency after we had instilled Viokase directly into the postcibal duodenum in two doses, one to deliver lipase at about 10% of normal secretory rates and the other at four times this rate. Direct duodenal instillation of neither the low nor the high dose of Viokase, nor the low dose of Viokase plus sodium bicarbonate, normalized fat absorption from the test meal; none of these duodenal instillations significantly improved fat absorption over that after the test meal plus orally ingested Viokase. Despite these various treatments, the patients excreted an average of 25.5 g of dietary fat as opposed to 2.1 g excreted by six normal subjects after the same meal. We conclude that more than just intragastric destruction of lipase underlies the frequent failure of orally ingested pancreatin to normalize fat absorption in pancreatic insufficiency.

Use of pancreatic Schilling test to determine efficiency of pancreatic enzyme delivery in pancreatic insufficiency

The pancreatic Schilling test (PST), a noninvasive, sensitive pancreatic function test, was studied to determine its ability to detect pancreatic proteolytic enzyme replacement in patients with pancreatic insufficiency. Seven subjects with well-documented pancreatic insufficiency and an abnormal PST consistent with pancreatic insufficiency were studied with three enzyme regimens: (1) Viokase (four tablets), (2) Pancrease (three capsules), and (3) Pancrease (10 capsules). The effect of cimetidine on the results of the PST with high-dose Pancrease was also determined in two subjects with pancreatic insufficiency and in two normal volunteers. The results of the investigation demonstrate that the PST is a sensitive noninvasive test for the presence of orally administered proteolytic enzymes in subjects with pancreatic insufficiency and in normals. Furthermore, the studies illustrate that the administration of enzymes in a form of enteric-coated microspheres does not enhance the delivery of proteolytic enzymes to the small intestine when compared to conventional high-dose enzyme replacement. Cimetidine appears to decrease the inactivation of the proteolytic enzymes in enteric-coated microspheres, suggesting that a low pH in the small intestine and stomach are responsible for the poor delivery of the enzymes into the small intestine.

Critical examination of therapeutic efficacy of a pH-sensitive enteric-coated pancreatic enzyme preparation in treatment of exocrine pancreatic insufficiency secondary to cystic fibrosis

In an attempt to critically examine the therapeutic efficacy of pH-sensitive enteric-coated pancreatic enzyme preparations in patients with pancreatic insufficiency due to cystic fibrosis, postprandial duodenal concentration and recovery of orally administered pancreatic enzymes, duodenal pH, and coefficient of fat absorption were determined in eight cases after ingestion of equivalent dosage of enteric-coated as well as conventional enzyme preparations. Ingestion of a pH-sensitive enteric-coated pancreatic enzyme preparation was accompanied with a significant (P less than 0.05) reduction in steatorrhea, as well as a lower mean concentration and recovery of lipase and trypsin activity in the postprandial duodenal samples. Furthermore, the intraluminal duodenal pH was noted to be below 4.0 during the postprandial period in all patients. These data suggest that in cystic fibrosis, the greater therapeutic efficacy of pH-sensitive enteric-coated preparations over conventional preparations may be related to the protection of pancreatic enzymes from the highly acidic milieu in the duodenum, allowing for possible bioavailability in the distal small intestine.

Study to compare the enzyme activity, acid resistance and dissolution characteristics of currently available pancreatic enzyme preparations

An in vitro study of currently available pancreatic enzyme preparations was carried out to compare the three main types of product available, these being simple pancreatin preparations, enteric coated tablets and enteric coated granules. Two products from each of these types were analysed to compare their enzyme contents. The enteric coated preparations were tested for acid resistance and their pH dissolution profiles were also investigated. The measured enzyme contents were generally higher than the declared values but products' enzyme declarations remain valid for comparison. As the BP declaration for protease does not include total protease this value may be misleading. Acid resistance and pH dissolution profiles varied both between the types of preparation and between the actual products tested. The enteric coated granule preparations were more resistant to acid and released their enzyme more rapidly once the pH threshold of dissolution was reached. Of the two enteric coated granule preparations, Creon (Duphar) was more resistant to acid and released its enzyme from a slightly lower pH value.

The use of a synthetic prostaglandin E1 analogue (misoprostol) as an adjunct to pancreatic enzyme replacement in cystic fibrosis

Eleven cystic fibrosis children (mean age, 9.6 years) were chosen at random to participate in a study to observe the effects of concurrently stimulating gastric/duodenal bicarbonate secretion and inhibiting gastric acid secretion, using a methylated prostaglandin E1 analogue in patients with pancreatic insufficiency and taking pancreatic enzymes. Percentage fat absorption in 3-day stool collections were calculated before and after commencing therapy with misoprostol, 400 micrograms/day in divided doses. We found a significant reduction in fat output (14.7 +/- 11.7 versus 7.5 +/- 3.5 g/day, p less than 0.05) in the study group as a whole and a significant reduction in steatorrhoeic level as a percentage of fat intake in all of the patients with abnormal base-line collections (23.1% versus 9.2%, p less than 0.002). We conclude that misoprostol should be considered in cystic fibrosis patients with steatorrhoea as a means of improving nutrient absorption.

Review: pancreatic enzyme replacement--applied physiology and pharmacology

The treatment of pancreatic steatorrhoea can often be improved by attention to the pathophysiological and pharmacological principles involved. Factors influencing the efficacy of pancreatic enzyme replacement include physiological characteristics of the individual patient and pharmaceutical characteristics of the supplement. Different patients may be best suited by different preparations and there is no overall 'best buy'. The new enteric-coated microsphere formulations are often most effective, but also more expensive than conventional preparations. Adjunctive H2-blockade can help appropriately selected patients with resistant steatorrhoea. Knowledge of the underlying cause may guide the choice of supplement and its dose, but trials of different regimens may prove necessary. Successful management, particularly of malnourished patients, involves optimization of dietary fat intake in addition to enzyme replacement.

Rational approach to long-term use of H2-antagonists

Although the approved indications for long-term histamine (H2) receptor-antagonists are limited to the management of hypersecretory states and prophylaxis against recurrent duodenal ulcer, these agents are often prescribed indiscriminately. Definitive guidelines concerning proper patient selection for prophylaxis against duodenal ulcer recurrence are lacking. Persons likely to benefit from maintenance therapy include those who smoke and those with a long duration of symptoms or prior history of an ulcer complication. Although not an approved indication, maintenance therapy to prevent recurrent gastric ulcer is appropriate for elderly persons receiving nonsteroidal anti-inflammatory drugs or in patients with poor cardiopulmonary status who may not tolerate surgery for an ulcer-related complication. The role of long-term H2-antagonist therapy in reflux esophagitis is not defined but may be appropriate in scleroderma and Barrett's esophagus. Finally, several miscellaneous conditions, including cystic fibrosis, Menetrier's disease, and pancreatic exocrine insufficiency, may benefit from long-term H2-antagonist therapy. Currently, clinical trials document the efficacy of maintenance therapy in duodenal ulcer for up to a three-year period; however, for gastric ulcer and chronic reflux esophagitis, the duration and benefit of long-term therapy is not established, and treatment regimens need to be individualized. Therapy may be required indefinitely in the miscellaneous states mentioned previously.

Conjugated bile acids in serum and secretions in response to cholecystokinin/secretin stimulation in children with cystic fibrosis

More than 80% of patients with cystic fibrosis have poor pancreatic function, and have large daily faecal bile acid losses. This has been postulated to lower luminal bile acid concentrations and adversely affect fat absorption. We studied, for the first time, quantitative individual conjugated duodenal bile acid secretion rates into the duodenum during cholecystokinin/secretin infusion in 55 cystic fibrosis patients and six controls, using a quantitative non-absorbable marker technique. We were able to show adequate duodenal total bile acid concentrations and normal secretion rates in these children. The bile acid secretion pattern in cystic fibrosis patients showed a marked increase in bile acid concentration during cholecystokinin/secretin infusion, to levels which were above the critical micellar concentration indicating that the gall bladder is a functional organ in this disease. The subsequent fall in secretion rate was similar to controls. We have documented a significantly raised glycine/taurine bile acid conjugation ration in duodenal juice from cystic fibrosis patients and suggest that the combined effects of lowered ileal pH and increased glycine conjugated proportion of bile acids may cause precipitation of bile acids leading to decreased fat absorption and large faecal bile acid losses. To further investigate bile acid secretion in children with cystic fibrosis, we modified the high performance thin layer chromatography/densitometry method to enable measurement of individual glycine and taurine conjugates in serum. In comparing cystic fibrosis patients and controls, we were able to determine a group of 18 (36%) with bile acid evidence of liver damage who also showed reduced bile acid secretion into the duodenum. We were unable to study changes in serum bile acids during cholecystokinin/secretin infusion because of the high level of bile acid contamination in Boots Secretin. Some patients showed raised fasting serum bile acid concentrations more than two years before changes in conventional liver function tests or clinically evident liver disease. We have shown fasting serum bile acids to be a sensitive measure of liver dysfunction in cystic fibrosis and postulate that raised proportions of glycine conjugated bile acids may be responsible for the high incidence of liver disease in cystic fibrosis.

Review of cimetidine drug interactions

The literature on cimetidine drug interactions has been thoroughly reviewed. Several different mechanisms have been proposed for cimetidine-related drug interactions. These mechanisms include: (1) impaired hepatic drug metabolism due to inhibition of hepatic microsomal enzymes, (2) reduced hepatic blood flow, resulting in decreased clearance of drugs that are highly extracted by the liver, (3) increased potential for myelosuppression when administered concurrently with other drugs capable of causing myelosuppression, and (4) altered bioavailability of acid-labile drugs. Cimetidine binds reversibly to the hepatic cytochrome P-450 and P-448 systems, resulting in decreased metabolism of drugs that undergo Phase I reactions (e.g., dealkylation and hydroxylation). In contrast, glucuronidation pathways are unaffected. The rapid onset and reversal of cimetidine's inhibition of hepatic metabolism indicates an effect on hepatic enzyme systems. Cimetidine also has been reported to decrease hepatic blood flow. Drugs that are highly extracted by the liver, such as propranolol, lidocaine, and morphine, may be postulated to have a decreased hepatic clearance. Cimetidine, through its effect on gastric pH, may increase the absorption of acid-labile drugs or may decrease the absorption of drugs. There have been reports of increased potential for myelosuppression when cimetidine is administered concurrently with drugs capable of causing bone marrow suppression. An understanding of the mechanisms involved in cimetidine drug interactions allows the clinician to prevent and predict these interactions.