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PubMed1995

Stimulation of butyrate absorption in the human rectum in vivo.

BACKGROUND: Models of short-chain fatty acid absorption have focused on the stimulation of sodium absorption, an effect mainly located in the proximal colon of man. With the present efforts to utilize butyrate enemas as a treatment of ulcerative colitis, it seemed important to assess the transport in the rectum. METHODS: Non-equilibrium dialysis of the rectum was applied by placing dialysis bags containing various electrolyte solutions in the rectum of volunteers for 30 min. In this period changes in ion concentrations were linear with time. Net absorption and secretion rates were calculated from the change in fluid composition. RESULTS: Sodium absorption was highest (24 +/- 8 mumol/cm2 h) in the presence of chloride and lowest (16 +/- 2 mumol/cm2 h) in the presence of bicarbonate and butyrate. Butyrate (70 mmol/l) was absorbed at a high rate of 7.1 +/- 2.2 mumol/cm2 h, independent on the presence of chloride, and was accompanied by increased bicarbonate secretion. Butyrate absorption increased to 9.6 +/- 1.8 mumol/cm2 h in sodium-free high-potassium media containing bicarbonate. CONCLUSION: The results show that it is possible to increase butyrate uptake by manipulation of the electrolyte composition in the rectal lumen. Maximal uptake occurred with an electrolyte composition that was similar to the natural rectal content. The information gathered could be useful in designing enemas for trial in ulcerative colitis, provided the findings can be confirmed in these patients.

Adult↗
PubMed1984

Allometry of water vapor absorption in two species of tenebrionid beetle larvae.

Water vapor absorption is compared in the two tenebrionid larvae Tenebrio molitor and Onymacris marginipennis. Thresholds for absorption and "absorption capacity," which depend on ion transport by Malpighian tubules, are consistently different over the entire size range of the two species. Because of lower thresholds, uptake rates of Onymacris are over double those of Tenebrio in larvae of the same size at identical ambient water activities. By contrast, passive determinants of uptake, rectal conductance, and morphometry are similarly scaled with size in the two species. A ventilatory mechanism of vapor entry into the rectum is proposed for both species, since the anal canal is too long and narrow for exclusively diffusional entry. Vapor uptake in relation to larval mass was described by a simple diffusion model through rectal tissue, where flux varied directly with surface area and inversely with the distance between the lumen and Malpighian tubules. Failure of rectal conductance to increase proportionally with body mass means that size-specific vapor uptake declines with larval size in both species.

Absorption↗
PubMedDate not supplied

Bioavailability of metronidazole in rabbits after administration of a rectal suppository.

The bioavailability of metronidazole in rabbits was studied using plasma concentration measurements after the administration of the drug in a hydrophilic (glycerogelatin) suppository form. The peak in the plasma concentration time curve occurred about 1 hour after administration, indicating that the rate of absorption is fast and equivalent to that observed in humans after oral administration. There was rapid elimination of the drug, as indicated by a relatively high elimination rate constant and low plasma half-life. The in vitro dissolution profile of the suppositories further confirms rapid absorption of the drug from the suppositories in the rectum. The presence of Tween 80 enhanced the in vitro release of metronidazole, but the presence of a hydrogenated vegetable oil lubricant (Lubritab) caused retardation in the drug release from the suppositories.

Administration, Rectal↗
PubMed1976

Protein absorption and ammonia production: the effects of dietary protein and removal of the colon.

1. The effect of increasing dietary protein content on the amount of faecal nitrogen was measured in six normal subjects and five subjects without functioning colons (three with ileostomy and two with ileo-rectal anastomosis). 2. There was a significant inontent in the subjects without functioning colons. 3. In normal subjects with intact colons, faceal N content was found to be lower than that in subjects without colons, and furthermore there was no significant variation with diet. 4. The source of the increase in faecal N with increased dietary protein content in subjects without functioning colons is discussed and the significance of these findings in relation to the efficiency of protein absorption is considered.

Ammonia↗
PubMed2003

The rationale for cecorectal anastomosis for slow transit constipation.

The most usual reconstruction after subtotal colectomy is ileo-rectal anastomosis, which requires the removal of the caecum. We propose the treatment of chronic slow-transit constipation with subtotal colectomy and antiperistaltic caecoproctostomy. The sparing of the caecum, the ileo-caecal valve and the distal ileal loop, leaving a physiologic reservoir, allowing the presence of colic bacterial flora which metabolizes the undigested starch and produces short chain fatty acids, should guarantee a normal stool consistency, normal absorption of water, sodium and vitamin B12 and the prevention of renal and gallbladder lithiasis. In 1992, we started a study on the outcome of 19 patients who had undergone subtotal colectomy and antiperistaltic caeco-rectal anastomosis for slow-transit constipation. The surgical procedure was carried out without any serious complications and without mortality. The mean clinical follow-up was 64 months (range 5-132). Six months after surgery, 13 patients reported normal bowel movements with solid stool consistency, 5 reported diarrhoea and the need for antidiarrhoeal agents, and one reported constipation easily controlled with laxatives. Fifteen patients considered their quality of life as having improved compared with that before surgery. Selection of patients justify such very satisfying results. It is well known that colic resection is effective only in the case of slow transit constipation, and thus a careful physiologic assessment is needed to rule out other causes of constipation, such as outlet obstruction syndrome.

Adult↗
PubMed1989

Chronopharmacokinetic study of valproic acid in man: comparison of oral and rectal administration.

Circadian stage-dependent changes of valproic acid (VPA) kinetics was examined after rectal administration comparing after oral dosing. Eight healthy volunteers took a single oral or rectal dose of VPA 400 mg, in a form of sodium valproate, on two occasions, at 8:30 A.M. or 8:30 P.M. Subjects were synchronized with diurnal activity and nocturnal rest as their usual life under standardized meal conditions. After oral administration, mean total VPA concentrations in plasma were significantly higher in the morning than in the evening during the absorption phase. Cmax tended to be higher, tmax was shorter (P less than 0.05) and absorption rate constant (ka) tended to be larger (0.05 less than P less than 0.1) for VPA in the morning than in the evening, although no difference was demonstrated in other pharmacokinetic values between morning and evening trials. After rectal administration, no significant difference was demonstrated in VPA kinetics between morning and evening trials. The rectal administration might have an advantage to eliminate the time-dependent changes of VPA kinetics. Thus the current practice of giving a rectal dose seems to be justified because the time-dependent changes in VPA kinetics observed after oral administration may be reduced without compromising therapeutic efficacy.

Administration, Oral↗
PubMed1994

Medicinal applications of cyclodextrins.

Some cyclodextrins are produced industrially, and available in pharmaceutical quality, at reasonable prices. Their medicinal use means mainly--but not exclusively--the complexation of problematic drugs (poorly soluble, unstable, irritating, difficult to formulate substances). The CD complexation generally results in improved wettability, dissolution, and solubility; improved stability; reduced side effects; or in mildering of other undesired properties (e.g., bitter tastes, bad smells). CDs can be used advantageously practically in any drug forms: oral, rectal, pulmonary, external, ocular, etc. formulations. In oral solid and liquid formulations the chemical and physical stability and bioavailability, but particularly the role of absorption is improved. With appropriate highly soluble chemically modified CDs aqueous parenteral formulations can be prepared from poorly soluble drugs. Using CDs the transdermal penetration or nasal absorption of such drugs becomes possible, which earlier could not be administered through these ways. The direct therapeutic effects of CDs (or their derivatives) are demonstrated in several examples as well as the use of beta CD as vehicle in tabletting.

Chelating Agents↗
PubMed2002

Bile flow response to repetitive heat stress in rats.

BACKGROUND & OBJECTIVES: Heat stress produces loss of absorptive surface area of the small intestine, including the ileum which is the site of bile acid absorption. This may cause diarrhoea on account of the possible bile acid malabsorption. To explore this possibility, the effect of high ambient temperature exposure on bile flow was studied in the warm acclimated albino rats. METHODS: Following heat exposure at 38 +/- 0.5 degrees C for 4 h/day, for up to 5 consecutive days, bile flow in the rats was measured gravimetrically under pentobarbital-induced anaesthesia, at steady rectal temperature (37 +/- 0.7 degrees C), and flow characteristics and rate were studied. RESULTS: The bile flow increased with the rise in rectal temperature (Tre) in an anaesthetized animal but, the relationship between the two was not linear; the flow nearly ceased if rectal temperature exceeded 43 degrees-44 degrees C. At steady, near normal, rectal temperature, bile flow showed fluctuations and, repetitive heat exposure led to a significant increase in bile flow. INTERPRETATION & CONCLUSION: Exposure to high ambient temperature modulates liver secretory function to enhance bile flow rate and increase bile acid absorptive load on the small intestine, whose absorptive function is known to be adversely affected in heat stress.

Animals↗
PubMed1983

Water vapor absorption in insects.

In common with other animals the principal examples of water transport in insects are to be found in processing food and in excretion. Some insects and other arthropods are able to absorb water vapor using preexisting buccal or rectal structures. This unique exploitation of atmospheric water depends on adequate areas for condensing water vapor and the capacity for considerable "uphill" water transport. All known uptake mechanisms depend on producing fluids of sufficiently low water activity to bring about condensation from a range of environmental humidities. In the best-understood examples (mealworms and their relatives) active KCl transport by the Malpighian tubules generates osmotic pressures sufficient to extract water from activities down to 0.88. A standing gradient model seems to describe the coupling in the tubular lumen between water flows and ion transport. Low water permeabilities and ion transport modulated with flow rate are unusual features of this coupling.

Absorption↗
PubMed1995

Pharmacokinetics of apomorphine in Parkinson's disease.

The pharmacokinetic properties of apomorphine in patients with Parkinson's disease are described. Apomorphine is lipophilic; it has a large volume of distribution and is rapidly cleared from plasma, with an elimination half life of 33 minutes. It is rapidly absorbed following subcutaneous injection, with peak levels achieved within 5-10 minutes in most patients. There is a large variation in absorption between patients but is more constant within patients following repeated dosing. Apomorphine rapidly equilibrates between plasma and brain. Like levodopa, the response tends to be largely "all or none"; larger doses produce a longer duration of effect within a 30-90 minute range. Apomorphine may be administered intranasally and sublingually; of these routes, the former is more quickly and completely absorbed. Other routes of administration, including rectally, are not as well absorbed but may also be used effectively.

Antiparkinson Agents↗
PubMed1984

Poisoning from dermal absorption of promethazine.

Two cases in which dermal absorption of promethazine hydrochloride resulted in a toxic neurologic syndrome are reported. The symptoms included central nervous system depression, acute excitomotor manifestations, ataxia and visual hallucinations. In addition, peripheral anticholinergic effects occurred. These symptoms are comparable with those of oral, intramuscular and rectal overdose of promethazine. The demonstrated risks of the topical use of promethazine outweigh any benefits.

Administration, Topical↗
PubMed1985

Secondary amyloidosis of the gastrointestinal tract: an electron microscopic study.

Biopsy specimens of the gastric antrum, duodenum, and rectum from three patients with secondary amyloidosis were examined by electron microscopy in an attempt to determine the ultrastructural distribution of amyloid filaments and to identify any secondary changes in the covering mucosal epithelial cells. The characteristic amyloid filaments were seen in the walls of submucosal arterioles and mucosal capillaries deposited within the basal lamina surrounding the endothelial cells. Filaments were also sometimes seen within the muscularis mucosa. the overlying gastric and rectal epithelial cells appeared normal, but numerous curved bacilli were seen in close contact with the microvilli of the surface epithelial gastric cells. Duodenal columnar absorptive cells were vacuolated and contained prominent lysosomes. These changes are probably degenerative and may explain, at least in part, the development of malabsorption in some patients with intestinal amyloidosis.

Adult↗
PubMed2000

Mucoadhesive suppositories of ramosetron hydrochloride utilizing Carbopol.

Suppositories are the preferable dosage form for patients at home or experiencing nausea. Serotonin (5-HT(3))-receptor antagonists are used to treat vomiting in intravenous or oral administration but not suppository form. Ramosetron hydrochloride (RAM) is a new 5-HT(3) antagonist which effectively inhibits vomiting, and we prepared RAM suppositories using Witepsol((R)) H-15 (H-15) containing Carbopol((R)) 934P (CP). The viscosity of suppository base and RAM release properties from suppositories were examined. Plasma RAM concentrations after administration of suppositories to rabbits were estimated and irritation of rectal tissues were observed. Antiemetic effects of suppositories were studied using ferrets. The base viscosity increased with addition of CP. Suppositories containing CP exhibited better absorption in rabbits compared to H-15 suppositories, correlated with release behavior. Suppositories containing 2% CP had 2.5 times larger AUC(0-24 h) than H-15 suppositories, and the MRT was prolonged by 5.8 h compared with i.v. administration. 10% CP suppositories administered to rabbits for 5 days did not irritate the tissues. Antiemetic studies indicated that 2% CP suppository of RAM might have the same effect as i.v. administration. These results suggest that RAM suppositories containing CP are safe and useful in once-a-day dosage form for treatment of chemotherapy-induced nausea.

Acrylic Resins↗