Laxatives: clinical pharmacology and rational use

Generational reproductive outcomes in Wistar rats maternally exposed to Ricinus communis oil at different stages of gestation

Fetal programming hypothesis presupposes that stimulus or insult acting during critical periods of uterine growth and development may permanently alter tissue structure and function. Ricinus communis oil (RCO) has been reported to possess/used as laxative, labor-inducing and estrogenic properties. Generational reproductive effects of maternal exposure to RCO was investigated in rats. A total of 25 pregnant rats randomly assigned to five equal groups were treated with distilled water (control, group 1), RCO (950 mg/kg p.o.) during gestation days (GD) 1-7, 7-14, 14-21 and 1-21, respectively. Birth weight, morphometric data, anogenital distance (AGD), pubertal age, sperm parameters, hormonal profile, organ weight and histopathology were determined in the first (F1) and second (F2) filial generations. Results showed a significant decrease (P<0.05) in birth weight/morphometric data in male pups from the GD 1-7 and 7-14 groups. AGD decreased significantly in RCO-treated F1 males. Pubertal age of F1 females decreased significantly (P<0.05) compared with controls. At postnatal day 90, F1 males from the RCO-treated group showed significant decrease in testis weight, body weight, sperm count, motility and normal morphology. Testosterone levels were significantly decreased in RCO-treated F1 males, which also showed testicular interstitial edema and epididymal hypospermia. Only pubertal indexes were altered in F2 rats. Maternal exposure to RCO at early gestation periods impaired androgen-mediated reproductive end points in the first generation of rats. RCO exhibits endocrine disrupting capabilities.

Pediatric Toxicology

Pediatric patients present unique concerns in the field of medical toxicology. First, there are medicines that are potentially dangerous to small children, even when they are exposed to very small amounts. Clinicians should be wary of these drugs even when young patients present with accidental ingestions of apparently insignificant amounts. Next, over-the-counter laxatives and syrup of ipecac, although not commonly considered abused substances, may be misused in both the setting of Munchausen's syndrome by proxy and in adolescents who have eating disorders. Their use should be considered in any gastrointestinal illness of uncertain origin. Finally, as the use of syrup of ipecac at home now has been discouraged by many, some have explored using activated charcoal at home as a new method of prehospital gastrointestinal decontamination. The literature examining activated charcoal and its use in this capacity is discussed.

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.

Mild dehydration: a risk factor of constipation?

Constipation defined as changes in the frequency, volume, weight, consistency and ease of passage of the stool occurs in any age group. The most important factors known to promote constipation are reduced physical activity and inadequate dietary intake of fibres, carbohydrates and fluids. Fluid losses induced by diarrhoea and febrile illness alter water balance and promote constipation. When children increase their water consumption above their usual intake, no change in stool frequency and consistency was observed. The improvement of constipation by increasing water intake, therefore, may be effective in children only when voluntary fluid consumption is lower-than-normal for the child's age and activity level. In the elderly, low fluid intake, which may be indicative of hypohydration, was a cause of constipation and a significant relationship between liquid deprivation from 2500 to 500 ml per day and constipation was reported. Dehydration is also observed when saline laxatives are used for the treatment of constipation if fluid replacement is not maintained and may affect the efficacy of the treatment. While sulphate in drinking water does not appear to have a significant laxative effect, fluid intake and magnesium sulphate-rich mineral waters were shown to improve constipation in healthy infants. In conclusion, fluid loss and fluid restriction and thus de-or hypohydration increase constipation. It is thus important to maintain euhydration as a prevention of constipation.

Prospective, randomized, parallel-group trial to evaluate the effects of lactulose and polyethylene glycol-4000 on colonic flora in chronic idiopathic constipation

BACKGROUND

Although lactulose and polyethylene glycol are osmotic laxatives widely used in the treatment of chronic constipation, no study has been conducted to compare their actions on the colonic bacterial ecosystem, which has an important influence on host health.

AIM

To assess the effects of lactulose and polyethylene glycol on the composition and metabolic indices of the faecal flora in patients with chronic idiopathic constipation.

METHODS

Sixty-five patients with chronic idiopathic constipation were included in this controlled, multi-centre, randomized, parallel-group study. Participants received lactulose (Duphalac) or polyethylene glycol-4000 (Forlax) powders for the first week at a fixed dosage at night (20 g/day); in the second week, patients were given the option to vary the dose according to efficacy and tolerance (10-30 g/day); for the last 2 weeks, treatment was administered at a fixed dosage based on the results of the second week (10-30 g/day). Stools were recovered for bacteriological analysis at days -1, 21 and 28.

RESULTS

Clinical efficacy and tolerance were similar with both treatments. In the lactulose group, an increase in faecal bifidobacteria counts (P = 0.04) and beta-galactosidase activity (P < 0.001) was observed from day -1 to day 28, whereas, in the polyethylene glycol group, there was a decrease in total short-chain fatty acids (P = 0.02), butyrate (P = 0.04), acetate (P = 0.02) and faecal bacterial mass (P = 0.001). No differences were observed in stools with regard to the following parameters: counts of Lactobacillus, clostridial spores, Bacteroides and enterobacteria, pH, biliary acids and neutral sterol concentrations.

CONCLUSIONS

Both lactulose and polyethylene glycol are efficacious and well tolerated. However, although lactulose can be considered as a pre-biotic in constipated patients, polyethylene glycol produces signs of decreased colonic fermentation in the stool.

Self-prescribed laxative use: a drug-utilization review

This study was conducted to determine the reasons for the choice of self-prescribed laxatives and to acquire information on how they were used and tolerated. From November 1999 to February 2000, 70 pharmacies, uniformly located throughout the Campania region of southern Italy, distributed a questionnaire to purchasers of over-the-counter laxatives. The average age of the (mostly female) respondents was 45.9 years; 23.8% were elderly. Among the 7324 individuals who completed the survey, 77.6% selected an oral product; 22.4% preferred rectal administration. A physician influenced the choice of a laxative in 37.7% of the cases, a pharmacist in 20.5%; other suggestions came from relatives (14%), acquaintances (12.1%), advertisements (11.7%), and miscellaneous sources (4%). Only 59.8% of respondents used these drugs correctly, and 58.2% consulted a physician or pharmacist because of constipation. Adverse effects, mainly gastrointestinal symptoms, occurred in 6.1% of those surveyed. The long-term use or abuse of laxatives can cause serious medical consequences, as well as mask diseases, delaying diagnosis and appropriate treatment. Physicians, pharmacists, and other health-care personnel should counsel patients on the proper use of these easily available, ubiquitous drugs.

Review article: the management of constipation in adults

The successful management of constipation depends on defining the patient's symptoms, excluding secondary causes, and characterizing the abnormality of defecation. Constipation without gut dilatation is found commonly in pregnancy, the elderly, and those with the irritable bowel syndrome. In addition, there is a group of patients that has intractable, severe idiopathic constipation. Some have 'slow transit' and open their bowels every 1-4 weeks. Others have a defecatory disorder with normal colonic transit. Constipation with gut dilatation is seen in Hirschsprung's disease, idiopathic megarectum and megacolon, chronic intestinal pseudo-obstruction and Chagas' disease. Constipation can also result from disturbance to the autonomic outflow of the gastrointestinal tract, and colonic function may be also affected by psychological factors. This review article discusses the presentation, investigation and management of patients with constipation.

Screening procedure for stimulant laxatives in urine using high-performance liquid chromatography with diode array detection

We describe a liquid chromatographic screening procedure for the detection of stimulant laxatives in urine. A 2-ml urine sample was incubated with 500 U of beta-glucuronidase for 2 h at 60 degrees C. The sample was acidified with sodium acetate (pH 5.0) and extracted with 5 ml of an isopropanol-chloroform (1:9) mixture. The organic layer was cleaned up further by washing with 5 ml disodium hydrogen-phosphate (pH 7.5) before being transferred to a conical tube and evaporated to dryness. The residue was reconstituted in 100 microliters mobile phase and 3 microliters were injected onto a Hewlett-Packard Hypersil ODS (5 microns) column. The ultraviolet absorbance of the eluent was monitored at 225 nm. Rhein, bisacodyl diphenol, bisoxatin diphenol, phenolphthalein, bisacodyl, bisoxatin and danthron all eluted within 6 min. The screen was evaluated using urine specimens obtained from 19 patients who claimed they had taken one or more of the laxatives under consideration within the past 48 h. Only two patients who claimed to have taken Coloxyl and Danthron showed negative results. Eighteen of twenty laxatives (90%) taken by the patients were detected and their identity verified by plotting post-run ultraviolet spectra. We therefore conclude that the screen is sufficiently reliable to be of help in the early detection of surreptitious abusers of stimulant laxatives.

Ultrastructure of mouse intestinal mucosa and changes observed after long term anthraquinone administration

In an attempt to study the relative toxicity of anthraquinonic laxatives on intestinal mucosa, we compared in mice the effects of fruit pulp containing sennosides A and B with those of a free anthraquinone, 1-8 dihydroxyanthraquinone. Observations have been made with transmission electron microscopy (EM) after 16 weeks of treatment with the two drugs. Although the doses used in this study were equipotent in terms of laxative activity, no damage to the intestinal tissue was observed with the sennosides. A number of changes, however, were detected in intestinal nervous tissues of all the animals treated with 1-8 dihydroxyanthraquinone, mainly in the form of vacuolisation of the axons, formation of lysosomal structures and in some cases appearances of fibrillar degeneration.

Actions of ricinoleic acid and structurally related fatty acids on the gastrointestinal tract. II. Effects on water and electrolyte absorption in vitro

Ricinoleic acid, the active component of castor oil, and related fatty acids were studied to determine their relative inhibitory effects on water and electrolyte absorption using everted hamster jejunal and ileal segments. Differences were found between hydroxylated and nonhydroxylated congeners as well as between cis and trans geometric isomers. At a mucosal concentration of 2.0 mM, the unsaturated fatty acids had the following rank order of potency on inhibition of water absorption: ricionoleate greater than or equal to ricinelaidate- greater than equal to linoleate greater than oleate greater than linelaidate greater than elaidate. Ricinoleyl alcohol was effective at 2.0 mM but the methyl ester of ricinoleic acid was ineffective at this concentration. Among a series of saturated fatty acids including palmitate, stearate, a mixture of 9- and 10-hydroxystearate, and 12-hydroxystearate, only the last compound had any inhibitory effect on water absorption. The results define those portions of the ricinoleic acid molecule required for its effect on water and electrolyte absorption and suggest that classification of this cathartic as an "irritant" or "stimulant" should be re-evlauated.