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PubMed2003

Lactulose production by beta-galactosidase in permeabilized cells of Kluyveromyces lactis.

Lactulose production from lactose and fructose was investigated with several commercial beta-galactosidases. The enzyme from Kluyveromyces lactis exhibited the highest lactulose productivity among the beta-galactosidases tested. The reaction conditions for lactulose production were optimized using cells that had been permeabilized by treatment with 50% (v/v) ethanol: cell concentration, 10.4 g l(-1); concentration of substrates, 40% (w/v) lactose and 20% (w/v) fructose; temperature, 60( degrees )C; pH 7.0. Under these conditions, the permeabilized cells produced approximately 20 g l(-1) lactulose in 3 h with a lactulose productivity of 6.8 g l(-1) h(-1). These results represent 1.3- and 2.1-fold increases in lactulose concentration and productivity compared with untreated washed cells. This is the first reported trial of enzymatic synthesis of lactulose using permeabilized yeast cells.

Cell Membrane Permeability↗
PubMed2006

Prospective randomized crossover trial comparing fibre with lactulose in the treatment of idiopathic chronic constipation.

BACKGROUND: Fibre is often recommended as the first-choice treatment but its effects can be uneven. The aim of the study was to compare the clinical efficacy and tolerability of fibre versus lactulose in outpatients with chronic constipation. METHODS: In a prospective randomized crossover trial, patients were randomized to receive fibre or lactulose for four weeks. Between treatments, patients had at least one week free of laxatives. RESULTS: 50 patients, of median age 50 years (range, 18-85) were recruited and 39 patients completed the trial. Compared to fibre, lactulose resulted in significantly higher mean bowel frequency (7.3, 95% CI 5.7 to 8.9 vs. 5.5, 95% CI 4.4 to 6.5; p=0.001) and stool consistency score (3.4, 95% CI 3.1 to 3.7 vs. 2.9, 95% CI 2.5 to 3.3; p=0.018). Scores for ease of evacuation were similar. The frequencies of adverse effects were not significantly different, but greater in the lactulose group. Mean patients' recorded improvement score was significantly higher after taking lactulose than fibre (6.2, 95% CI 5.5 to 7.0 vs. 4.8, 95% CI 4.0 to 5.9; p=0.017). Of the 39 patients who completed the trial, 24 (61.5%) preferred lactulose and 14 (35.9%) preferred fibre. CONCLUSIONS: Lactulose had better efficacy than fibre for chronic constipation in ambulant patients, although both treatments were equally well tolerated in terms of adverse effects.

Adolescent↗
PubMed2005

Comparison of inulin and lactulose as reference standards in the breath hydrogen test assessment of carbohydrate malabsorption in patients with chronic pancreatic exocrine insufficiency.

Although often used as a reference standard in the breath hydrogen test (BHT), lactulose fermentation produces more hydrogen, compared to starch, and may therefore not be ideal. This study compares inulin with lactulose as reference standard in the study of carbohydrate malabsorption. Seventeen patients with malabsorption due to chronic pancreatitis and 15 normal controls were studied. Following overnight fasts, BHTs were performed after ingesting 10 g lactulose, 10 g inulin, and 200 g (16 g highly resistant starch) maize meal. Lactulose fermentation produced significantly more hydrogen than inulin in patients with malabsorption (97 +/- 20 vs 45 +/- 22 ppm x hr; P < 0.05) and controls (43 +/- 18 vs 21 +/- 10 ppm x hr; P < 0.05). Patients produced more hydrogen than controls with both standards (lactulose, 97 +/- 20 vs 43 +/- 18 ppm x hr, P < 0.05; inulin 45 +/- 22 vs 21 +/- 10 ppm x hrs; P < 0.05), suggesting adaptation of the colonic flora. Calculated CHO malabsorption was 2.5 +/- 0.8 vs 5.2 +/- 3.8 g with lactulose and 5.2 +/- 3.1 vs 11.2 +/- 9.6 g with inulin as standards in controls and patients, respectively (P < 0.05). Lactulose produces more breath hydrogen than inulin. Calculation of CHO malabsorption using these standards is therefore not comparable.

Adult↗
PubMed1988

Lactulose detoxifies in vitro short-chain fatty acid production in colonic contents induced by blood: implications for hepatic coma.

Short-chain (C2-C6) fatty acids constitute the major anions of colonic contents. Acetate is nontoxic in contrast to C(3)4-C6 fatty acids, which induce coma in animals and have been reported to be of importance in the development of hepatic coma in humans. An in vitro fecal incubation system was used to demonstrate how blood, hemoglobin, albumin, lactulose, galactose, fructose, and glucose influence short-chain fatty acid production in the colon. Blood, hemoglobin, and albumin caused increased production of all C2-C6 fatty acids, with the most pronounced increase (fourfold) in C4-C6 fatty acids. Lactulose was converted to acetate only, as were its monosaccharide components, D-galactose and D-fructose. In assays incubated with blood, the production of C4-C6 fatty acids was completely inhibited by lactulose, D-galactose, D-fructose, and D-glucose, respectively, whereas the production of acetate was increased. Lactulose thus "detoxified" the profile of short-chain fatty acids produced in the presence of blood and proteins, indicating that colonic fermentative bacteria prefer lactulose to blood when both substrates are available. The effect of lactulose in the treatment of hepatic coma caused by episodes of gastrointestinal bleeding may therefore be due to a shift in bacterial metabolism from blood or proteins, or both, to lactulose in the colon, resulting in a simultaneous reduction in toxic nitrogenous and organic acid products.

Bacteria↗
PubMed1987

Lactitol versus lactulose in the treatment of chronic hepatic encephalopathy. A double-blind, randomised, cross-over study.

Lactitol is a disaccharide analogue of lactulose which is available as a pure crystalline powder. The efficacy of lactitol in the treatment of chronic hepatic encephalopathy was assessed in 9 cirrhotic patients in a randomised, double-blind, cross-over comparison with lactulose. The sugars were dispensed in solutions, identical in taste and appearance and with similar physico-chemical properties, which contained either 66.7 g/100 ml of lactitol or 66.7 ml (44.5 g)/100 ml of lactulose syrup. Patients were treated for periods of 3 months with each sugar, during which time they were monitored frequently by use of a number of clinical, psychometric and laboratory variables. The sugar solutions were dispensed in an initial dose of 0.75 ml/kg which was adjusted, as necessary, in order to produce two semi-soft stools per day. An adequate catharsis was achieved with a mean (+/- 1 SD) equivalent daily dose of 31.9 +/- 11.2 g of lactitol or 32.9 +/- 16.7 ml (21.9 +/- 11.1 g) of lactulose syrup. Both sugars were equally as effective in the treatment of this condition, even though events likely to cause decompensation arose in 5 patients during treatment with lactitol but in only 1 during treatment with lactulose. Side effects appeared to be more frequent during treatment with lactulose, despite the fact that the parent sugar was diluted in the trial solution; thus 5 patients experienced excessive flatulence and 8 experienced diarrhoea on lactulose compared with only 2 and 4 on lactitol, respectively. In all cases the excessive flatulence occurred independently of sugar dosage whereas the development of diarrhoea was dose-related.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Effect of the protein, citrate and phosphate content of milk on formation of lactulose during heat treatment.

Milk ultrafiltrate and milks of varying protein, citrate and phosphate concentrations were heated in sealed containers. Protein was found not to be involved in the mechanism of formation of lactulose, but increasing the protein content of milk reduced the concentration of lactulose after heating. This was considered to be due to increased condensation of lactose and lactulose with amino groups of the protein. Less lactulose was formed in milk ultrafiltrate than in skimmed milk accorded the same heat treatment, which was attributed to the buffering capacity of the milk protein in skimmed milk. Activation energies for lactulose formation in skimmed milk and in ultrafiltrate were 128 and 131 kJ/mol respectively. Citrate and phosphate catalysed the formation of lactulose. It is proposed that the formation of free lactulose in heated milk and ultrafiltrate proceeds exclusively by the Lobry de Bruyn-Alberda van Ekenstein transformation with the naturally occurring phosphate and citrate acting as base catalysts.

Animals↗
PubMed2003

Effect of colonic lactulose availability on the timing of drug release onset in vivo from a unique colon-specific drug delivery system (CODES).

PURPOSE: To test the hypothesis that the onset of drug release in vivo from a unique colon-specific drug delivery system (CODES) would depend on the colonic availability rate of lactulose. The site specificity of drug release in canine GI tract was also estimated. METHODS: CODES tablets were prepared by tableting the granulation or acetaminophen and lactulose, followed with film coating. The pharmacokinetic performance of different CODES formulations was evaluated in six beagle dogs under fasted conditions. The release of acetaminophen and lactulose was also characterized in vitro. RESULTS: The onset of acetaminophen release in beagle dogs was found to be dependent on the coating level of Eudragit E and lactulose loading in the core tablet. At Eudragit E coating levels of 4%, 8% and 12% (coating weight gain), the onset of in vivo drug release occurred 5.5 (+/- 1.9) h. 4.8 (+/-1.0) h. and 7.5 (+/-1.0) h, respectively, after dosing. A similar trend was observed when the loading of lactulose in the core tablet decreased from 78% to 58% and 38%. However, the rate and extent of acetaminophen absorption did not vary significantly in each situation based on the values of AUC and Cmax. CONCLUSION: The onset of drug release in vivo from CODES tablets is predominantly dependent on colonic availability rate of lactulose because drug release from this system is triggered by localized drop of colonic pH from the fermentation of lactulose.

Acetaminophen↗
PubMed1997

Evaluation of oro-coecal transit time: a comparison of the lactose-[13C, 15N]ureide 13CO2- and the lactulose H2-breath test in humans.

OBJECTIVE: The lactulose H2-breath test is the most widely used non-invasive approach for evaluation of orocoecal transit time (OCTT). In the present study, doubly-labelled lactose-[13C, 15N]ureide (DLLU) was synthesized to investigate the OCTT in comparison to the conventional lactulose H2-breath test. Additionally the bacterial breakdown rate (BBR) and rate of elimination and the metabolic pathways of the cleavage products of DLLU (13CO2, [15N]urea, and 15NH3) were investigated. DESIGN AND SUBJECTS: In a first study, DLLU was administered as a single oral-pulse-labelling (dosage: one gram) either without and after pretreatment of five grams of unlabelled lactoseureide (LU) on the day prior to the study to twelve healthy adult volunteers after breakfast. Breath and urine were collected in one and two hour-intervals, respectively, over a one-day period. 13C-enrichment in breath as well as 15N-enrichment in urine fractions were measured by continuous flow-isotope ratio mass spectrometry (CF-IRMS). In a second study, lactulose was administered to the same subjects (dosage: ten grams). Breath was collected in quarter, half and one hour-intervals over a ten hour-period. Hydrogen concentration in breath was analysed using an electrochemical detector. RESULTS: The comparison of the lactose-[13C]ureide 13CO2-breath test and the lactulose H2-breath test showed that the mean increase of the 13C-enrichment in CO2 occurred 1.18 h later than the mean increase of H2 in breath. The resulting OCTTs derived from the two methods were 3.02 +/- 1.4 and 1.84 +/- 0.5 h (P < 0.05) and the corresponding BRs were 9.63 +/- 3.4 and 6.07 +/- 1.7 h (P < 0.01), respectively. The 15N-enrichment of urinary urea and ammonia without and after pretreatment with LU started between two and three hours after DLLU-administration. The cumulative percentage urinary excretion of the 15N- and 13C-tracer was 29.9% and 13.6% respectively, and was slightly increased after LU-pretreatment to 32.1% and 14.6% of the dose administered. A total of 35.2% of the 13C was found to be exhaled and remained approximately constant after LU-pretreatment (36.2%). CONCLUSIONS: The use of the lactulose H2-breath test for evaluation of the OCTT showed a statistically significant shortening of 1.18 h in comparison to the lactose-[13C]ureide 13CO2-breath test in healthy adults. The most important limitations of the lactulose H2-breath test are its low specificity and sensitivity due to dose-dependent accelerations of OCTT, interfering H2-rise from malabsorbed dietary fibre and H2-non-producers. In contrast, our lactose-[13C]ureide 13CO2-breath test was confirmed to avoid these disadvantages and to yield reliable results. This test is recommended especially if higher sensitivity and specificity is required, if IRMS-technique is available and if lactulose H2-tests lead to insufficient results.

Breath Tests↗
PubMed2003

Abdominal distension after colonic lactulose fermentation recorded by a new extensometer.

Colonic lactulose fermentation induces bloating, but whether it also causes abdominal distension is not known. The aim of this study was to assess the effect of colonic lactulose fermentation on abdominal girth using a new extensometer. We recorded abdominal girth in 24 healthy subjects by means of an extensometer that measures the phase shift of an ultrasound wave propagating in a tube encircling the abdomen. The recordings were continuously made for 3 h after the ingestion of 100 mL of tap water with (16 subjects) or without (eight subjects) 10 g of lactulose. Every 10 min, H2 in the breath was analysed and the intensity of bloating was recorded. Bloating was never reported after water ingestion, whereas it was reported by 10 subjects after lactulose ingestion (P = 0.002). The mean +/- SD changes in abdominal girth in comparison with resting conditions were statistically significant after lactulose ingestion (3 +/- 2.9 mm; P = 0.002) but not after water ingestion (-0.2 +/- 2.7 mm; P = 0.82). The area under the curve of the changes in abdominal girth after lactulose were significantly greater than after water ingestion (P = 0.03). In conclusion, colonic lactulose fermentation induces bloating and abdominal distension. The new extensometer is useful for continuously recording changes in abdominal girth.

Abdomen↗
PubMed1997

Clinical efficacy of lactulose in cirrhotic patients with and without subclinical hepatic encephalopathy.

Seventy-five cirrhotic patients with hyperammonemia in the past or at the time of the study were randomly divided into two groups (treated with lactulose or nontreated) in 14 hospitals in Japan. Thirty-six cirrhotic patients were diagnosed as having subclinical hepatic encephalopathy (SHE), and 39 were diagnosed as non-SHE. SHE was diagnosed when the results of all three of the quantitative psychometric tests used (number connection test, and symbol digit and block design tests of the Wechsler adult intelligence scale [revised]) were abnormal as compared with age-matched normal values. The mean number of abnormal psychometric test results and the prevalence of SHE were used for a quantitative evaluation of the efficacy of the lactulose treatment. Twenty-two of the SHE patients were treated with lactulose (45 mL/d) for 8 weeks, and the other 14 SHE patients did not receive lactulose. In the SHE patients administered lactulose, the results of the quantitative psychometric evaluation were significantly improved at 4 and 8 weeks after the beginning of the lactulose administration. The SHE had disappeared in 10 (50%) of the 20 treated patients at week 8, but it persisted in 11 (85%) of the untreated 13 patients. We concluded that lactulose treatment in cirrhotic patients with SHE is effective with respect to psychometric tests.

Administration, Oral↗
PubMed1996

The effect of lactulose on DNA damage induced by DMH in the colon of human flora-associated rats.

Germ-free rats were fed purified diets containing sucrose (0.3%, wt/wt) as control or the synthetic disaccharide lactulose (0.3% wt/wt) and were then dosed orally with a human fecal suspension. After five weeks on the diets, these "human flora-associated" rats were transferred to diets in which the sucrose or lactulose level was raised to 3% (wt/wt). Four weeks later, the rats from each dietary group were dosed orally with saline (controls) or 1,2-dimethylhydrazine dihydrochloride (DMH, 15 mg/kg). Sixteen hours after the carcinogen dose, the rats were killed, colon cells were isolated, and the degree of DNA damage in the cells was assessed using the single cell microgel electrophoresis (Comet) assay. Samples of cecal contents were also removed from the saline-treated rats to determine changes in composition of the gut microflora. No significant diet-related differences in cecal bacterial numbers were observed, although there was a trend for the numbers of lactobacilli to be higher in the lactulose-fed animals. DNA damage in colon cells was quantified by measurement of the length of the cellular DNA image after electrophoresis, and the evaluated cells were assigned to classes according to the degree of damage: undamaged (< 40 microns), moderately damaged (40-80 microns), or severely damaged (> 80 microns). There were no significant diet-related differences in DNA damage in colon cells from rats treated with saline. Treatment with DMH induced a highly significant increase in DNA damage in sucrose- and lactulose-fed rats. However, in the rats treated with DMH, the degree of DNA damage was significantly (p < 0.05) less in the lactulose-fed animals than in those given the sucrose diet, as evidenced by a decrease in the percentage of cells with severe damage. In the sucrose-fed rats, severely damaged cells accounted for 33% of the total compared with only 12.6% in the lactulose-fed DMH-treated animals. The results of this study, which was performed in human flora-associated rats to provide data of relevance to humans, indicate that lactulose consumption offered a degree of protection from the genotoxic effects in the colonic mucosa of a known colon carcinogen.

1,2-Dimethylhydrazine↗
PubMed1997

Bifidobacterium longum and lactulose suppress azoxymethane-induced colonic aberrant crypt foci in rats.

Bifidobacterium longum has been shown to afford protection against colon tumorigenesis. Lactulose, a keto analog of lactose, serves as a substrate for preferential growth of Bifidobacterium. It is not known whether feeding lactulose along with B. longum will have any advantage over feeding of B. longum alone. To test this combination effect, 61 male Fisher 344 weanling rats were divided into four groups of 15 rats each (16 in the control group) and assigned to one of the following four diets for 13 weeks: (i) AIN76A (control, C); (ii) C + 0.5% B. longum (C+Bl, containing 1 x 10(8) viable cells/g feed); (iii) C + 2.5% lactulose (C+L); (iv) C + 0.5% B. longum + 2.5% lactulose (C+Bl+L). All animals received a s.c. injection of azoxymethane at 16 mg/kg body wt at 7 and 8 weeks of age. Colons of 10 rats from each dietary group were analyzed for aberrant crypt foci (ACF), which are preneoplastic markers. Colonic mucosa and livers from five rats were analyzed for glutathione S-transferase (GST, a Phase II enzyme marker). Results indicate that feeding of lactulose and B. longum singly and in combination reduces the number of ACF (P = 0.0001) and the total number of aberrant crypts significantly (P = 0.0005). The total number of ACF in diets C, C+Bl, C+L and C+Bl+L were 187 +/- 9, 143 +/- 9, 145 +/- 11 and 97 +/- 11 respectively. There was no significant difference in weight gain among treatments. Colonic mucosal GST levels were significantly (P = 0.05) higher in the Bl and L groups compared with group C. Initially there was a mild diarrhea in lactulose-fed rats. There was a positive correlation between higher cecal pH and number of ACF. Results of the study indicate that Bifidobacterium and lactulose exert an additive antitumorigenic effect in rat colon.

Animal Feed↗
PubMed1997

Effect of lactulose on short-chain fatty acids and lactate production and on the growth of faecal flora, with special reference to Clostridium difficile.

Lactulose exerts a beneficial effect on hepatic encephalopathy by decreasing toxic short-chain (iC4-nC6) fatty acid (isobutyrate, butyrate, isovalerate, valerate, isocaproate and caproate) production. However, the precise mechanism by which lactulose exerts this effect remains uncertain. This study investigated the effect of lactulose on faecal flora, particularly Clostridium difficile, which produces mostly iC4-nC6 fatty acids. An in-vitro faecal incubation system was used to estimate how lactulose influences production of short-chain (C2-nC6) fatty acids and lactate. Faecal specimens were collected from patients with liver cirrhosis, who carried C. difficile in the colon. Supplementation of lactulose along with blood in faecal specimens decreased iC4-nC6 fatty acids production and increased acetate and lactate production, resulting in increased faecal acidity. These changes were statistically significant when compared with supplementation by blood alone. Quantitative faecal culture demonstrated that lactulose supplementation suppressed the growth of C. difficile and Bacteroides spp. (B. fragilis group), iC4-nC6 fatty acids-producing organisms. These results suggest that decreased faecal levels of iC4-nC6 fatty acids after lactulose supplementation may be related to suppression of iC4-nC6 fatty acids-producing faecal organisms, especially C. difficile.

Aged↗
PubMed2006

Polyethylene glycol 4000 vs. lactulose for the treatment of neurogenic constipation in myelomeningocele children: a randomized-controlled clinical trial.

AIM: To compare the therapeutic effectiveness and tolerability of low daily doses of polyethylene glycol 4000 vs. lactulose in the treatment of neurogenic constipation in children with myelomeningocele. METHODS: Sixty-seven children with chronic neurogenic constipation were randomized allocated to receive either polyethylene glycol 4000 (0.50 g/kg) or lactulose (1.5 g/kg) for 6 months. Patients or their parents reported frequency and modality of evacuation and side effects on a diary card. Primary outcome was bowel frequency > or =3/week, and the second one was side effects at the end of treatment. RESULTS: Complete remission of constipation was reported by a significantly (P < 0.01) higher number of patients treated with polyethylene glycol compared with lactulose. At the end of the study, 46% patients of polyethylene glycol group and 22% of the lactulose group were asymptomatic. Compared with lactulose, patients treated with polyethylene glycol reported higher bowel frequency (5.1 vs. 2.9 bowel movements/week, P < 0.01) and reduction of encopresis. Neither lactulose nor polyethylene glycol caused clinically-significant serious side effects and palatability was similar. CONCLUSIONS: Polyethylene glycol 4000 compared with lactulose provided a higher success rate, without significant side effects, for the treatment of constipation in myelomeningocele children.

Analysis of Variance↗
PubMed1988

Inhibition of secondary bile acid formation in the large intestine by lactulose in healthy subjects of two different age groups.

Secondary bile acids have been implicated in colonic carcinogenesis. Transformation of primary into secondary bile acids (7 alpha-dehydroxylation) in the large bowel is a pH-dependent process. Inhibition of this reaction could be achieved by lowering colonic pH. We, therefore, studied the effects of lactulose (a non-absorbable disaccharide), which is capable of acidifying colonic contents, on secondary bile acid metabolism. Because this metabolism is age dependent, lactulose was given (0.3 g kg-1 twice daily for 12 weeks) to nine middle-aged (age 31-54 years; mean 45.7) and ten elderly subjects (age 56-81 years; mean 66.4). Twice before, and after 6 and 12 weeks' lactulose administration, biliary and faecal bile acids, whole gut transit time, faecal weight and dry weight, and faecal pH were recorded. The concentration of (iso)lithocholic and deoxycholic acid in faeces was higher in elderly subjects (P less than 0.05) but the excretion was comparable. After lactulose the concentration and excretion of the major secondary bile acids decreased. The primary bile acid fraction rose from 5% before, to more than 20% after, lactulose (P less than 0.05). Faecal weight increased and faecal dry weight decreased, resulting in a higher faecal water output during lactulose. Whole gut transit time did not change. The faecal pH dropped after 6 (P less than 0.05) and further after 12 weeks' lactulose (P less than 0.05). The percentage deoxycholic acid in bile was higher, and cholic acid lower, in elderly subjects (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Lactitol in the treatment of chronic hepatic encephalopathy: an open comparison with lactulose.

Lactulose is currently the drug of choice for the treatment of hepatic encephalopathy. It is, however, only available as a syrup which is contaminated with other sugars. Consequently patients may express aversion to its excessively sweet taste and many experience nausea because of its hyperosmolarity. Lactitol is a disaccharide analogue of lactulose which can be produced as a pure crystalline powder with a low relative sweetness. Theoretically it should have the same therapeutic effects as lactulose but fewer side effects. Five patients with chronic hepatic encephalopathy on maintenance lactulose were monitored clinically, psychometrically, and by measurement of venous blood ammonia, electroencephalogram mean cycle frequency, and cerebral blood flow during three months treatment with lactulose and a similar period on lactitol. Lactitol was at least as efficacious as lactulose but was more acceptable because its cathartic effect was more predictable, its formulation was more convenient and its less sweet taste preferred. Lactitol is the ideal successor to lactulose for treatment of this condition.

Adult↗
PubMed1990

Lactulose inhibits endotoxin induced tumour necrosis factor production by monocytes. An in vitro study.

Preoperative oral treatment with lactulose is used to prevent complications after surgery in patients with obstructive jaundice. The effect is perhaps the result of an inactivation of gut derived endotoxins but the exact mechanism of action is, however, unknown. Tumour necrosis factor is an important mediator of endotoxin toxicity. The cytokine tumour necrosis factor is mainly produced by mononuclear phagocytes. In this study, the effect of lactulose on the endotoxin induced tumour necrosis factor release by monocytes was investigated. The direct effect of lactulose on endotoxin was tested in a chromogenic limulus amoebocyte lysate assay. Polymyxin B a known inactivator of endotoxin was used as control in both experiments. Lactulose has a limited capacity to inactivate endotoxin as measured in the endotoxin assay. In contrast lactulose significantly reduced endotoxin induced tumour necrosis factor production by monocytes. In conclusion lactulose inhibits tumour necrosis factor production by a direct inhibitory effect on monocytes, rather than by inactivation of endotoxin. Because tumour necrosis factor is an important mediator of endotoxin toxicity, this inhibitory effect could explain the beneficial effect of lactulose in obstructive jaundice.

Cells, Cultured↗
PubMed1989

Studies of osmotic diarrhea induced in normal subjects by ingestion of polyethylene glycol and lactulose.

The purpose of these studies was to gain insight into the pathophysiology of pure osmotic diarrhea and the osmotic diarrhea caused by carbohydrate malabsorption. Diarrhea was induced in normal volunteers by ingestion of polyethylene glycol (PEG), which is nonabsorbable, not metabolized by colonic bacteria, and carries no electrical charge. In PEG-induced diarrhea, (a) stool weight was directly correlated with the total mass of PEG ingested; (b) PEG contributed 40-60% of the osmolality of the fecal fluid, the remainder being contributed by other solutes either of dietary, endogenous, or bacterial origin; and (c) fecal sodium, potassium, and chloride were avidly conserved by the intestine, in spite of stool water losses exceeding 1,200 g/d. Diarrhea was also induced in normal subjects by ingestion of lactulose, a disaccharide that is not absorbed by the small intestine but is metabolized by colonic bacteria. In lactulose-induced diarrhea, (a) a maximum of approximate 80 g/d of lactulose was metabolized by colonic bacteria to noncarbohydrate moieties such as organic acids; (b) the organic acids were partially absorbed in the colon; (c) unabsorbed organic acids obligated the accumulation of inorganic cations (Na greater than Ca greater than K greater than Mg) in the diarrheal fluid; (d) diarrhea associated with low doses of lactulose was mainly due to unabsorbed organic acids and associated cations, whereas with larger doses of lactulose unmetabolized carbohydrates also played a major role; and (e) the net effect of bacterial metabolism of lactulose and partial absorption of organic acids on stool water output was done dependent. With low or moderate doses of lactulose, stool water losses were reduced by as much as 600 g/d (compared with equimolar osmotic loads of PEG); with large dose, the increment in osmotically active solutes within the lumen exceeded the increment of the ingested osmotic load, and the severity of diarrhea was augmented.

Adult↗