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PubMed1991

Bladder substitutes controlled by the anal sphincter: a comparison of the different absorption potentials.

A comparative study of the absorption potentials of the simple rectal bladder (10 patients), modified rectal bladder (20) and ureterosigmoidostomy (10) was done with intrarectal instillation of 22sodium. Results indicate that absorption is significantly greater among patients with ureterosigmoidostomy. The emptying patterns of ureterosigmoidostomy and the modified rectal bladder were also studied by ascending scintigraphy with 99mtechnetium. Evidence was provided that in cases with ureterosigmoidostomy the isotope is distributed throughout the entire colon. These studies proved the role of the colorectal valve in preventing reflux of urine from the rectum to the proximal colon. Consequently, the surface area of colonic mucosa exposed to urine is decreased and the rate of reabsorption is limited.

Absorption↗
PubMed1975

Plasma levels of diazepam after parenteral and rectal administration in children.

Plasma levels of diazepam and N-desmethyldiazepam were investigated in 19 children by a gas chromatographic method permitting the use of capillary sample. Intravenous administration was studied in 3 children and the plasma level curves showed a rapid decline during the first hour. Absorption and elimination after rectal administration of a solution in 16 children were similar to those after intramuscular administration. Diazepam given by suppository to 5 children gave much lower plasma levels and delayed time to peak levels. Recurrence of seizures in 2 children indicated that the anticonvulsants plasma level was of the order of 150 to 200 mug/liter. No significant side effects were observed. Thus rectal administration of a solution of diazepam is a practical method to arrest convulsions in children.

Child↗
PubMed1988

[Route and preparation of 5-Fu administration as preoperative adjuvant chemotherapy in rectal cancer. I. Concentration and distribution of 5-Fu in tissues monitored by 14C-isotopically tagged 5-Fu].

Experimental studies on more rational route and preparation of preoperative administration of 5-Fu were undertaken from March 1981 to June 1985. The experimental observation shows that intrarectal administration of radioisotope 14C tagged 5-Fu (suppository and emulsion) produces a much higher concentration in the rectal wall and mesenteric lymph nodes compared with its intravenous administration (40 rabbits) and produces a much higher concentration in cancer tissue than in surrounding tissues and in mesenteric lymph nodes than in the inferior mesenteric veins (4 patients). These findings favor the attenuation or destruction of cancer cells in the tumor and regional lymph nodes-the main route of spread. Also, after intrarectal administration of 14C tagged 5-Fu, its concentration in the lung, liver and bone marrow is much lower than that after intravenous administration (40 rabbits), and hence systemic toxicity is decreased. The above results indicate that the intrarectal route stands better than the conventional intravenous route for 5-Fu preoperative adjuvant chemotherapy in rectal cancer. Administration of 5-Fu emulsion produces a higher concentration in the rectal wall and mesenteric lymph nodes than that of 5-Fu suppository and peak concentration also appears earlier, i.e. 2 hours after the administration of 5-Fu emulsion. This will lessen the interference of 5-Fu absorption owing to its premature evacuation, indicating that emulsion is a better form for intrarectal 5-Fu.

Absorption↗
PubMed1989

Absorption of 5'-deoxy-5-fluorouridine from colon.

Rectally administered 5'-deoxy-5-fluorouridine (dFUR) is active against transplanted dimethylhydrazine-induced colon tumor in rats. This study investigated the disposition of dFUR in normal non-tumor-bearing rats after rectal administration (350 or 700 mg/kg). An intravenous (iv) bolus injection of [5'-3H]dFUR (28.2 muCi, 0.43 micrograms) was given 5 min after the rectal dose (700 mg/kg) to determine the dFUR clearance (CL). Blood and fecal samples were analyzed by high-pressure liquid chromatography and liquid scintillation. After the iv tracer dose, the CL was 19 ml/min/kg and the terminal half-life was 50 min. After a 700-mg/kg rectal dose, the terminal half-life was 430 min, the bioavailability was 30%, and the fraction of the dose recovered in 24-hr feces was 34%. After a 350-mg/kg dose, absorption was apparently not completed at 12 hr, as indicated by a lack of decline in blood concentration. The bioavailability of the 350-mg/kg dose exceeded 16%. The absorption of dFUR (700 mg/kg) from the colon was analyzed by the Loo-Riegelman method: the absorption half-life was 550 min. The terminal half-life after the rectal dose was much slower than that after the iv tracer dose but similar to the absorption half-life. These data indicate that dFUR was absorbed from the colon, that the absorption process was the rate-limiting step of its disposition after rectal administration, and that the slow absorption gave a sustained drug concentration in blood.

Animals↗
PubMed1995

Immunosuppressive effect induced by intraperitoneal and rectal administration of boar seminal immunosuppressive factor.

The immunosuppressive component was isolated from boar seminal vesicle secretion and administered i.p. or rectally to male mice. By means of the immunofluorescent method, the seminal immunosuppressive component was found on the membranes of 50-70% of white blood cells of treated mice the first day after i.p. and the third day after rectal administration. The immunosuppressive component was observed on the membranes of 10-20% of white cells even at the 17th day after treatment. Intraperitoneal or rectal administration of the immunosuppressive component led to a decrease in the white cell concentration in blood of treated mice. These findings indicate that rectal deposition of semen may compromise some aspects of the immune system and may be an important cofactor in the development of viral or bacterial infections among homosexual men.

Absorption↗
PubMed2003

Pharmacokinetics and plasma concentrations of acetylsalicylic acid after intravenous, rectal, and intragastric administration to horses.

Six healthy adult horses (5 mares and 1 stallion) were given a single dose of acetylsalicylic acid (ASA), 20 mg/kg of body weight, by intravenous (IV), rectal, and intragastric (IG) routes. Serial blood samples were collected via jugular venipuncture over a 36-h period, and plasma ASA and salicylic acid (SA) concentrations were determined by high-performance liquid chromatography. After IV administration, the mean elimination rate constant of ASA (+/- the standard error of the mean) was 1.32 +/- 0.09 h(-1), the mean elimination half-life was 0.53 +/- 0.04 h, the area under the plasma concentration-versus-time curve (AUC) was 2555 +/- 98 microg x min/mL, the plasma clearance was 472 +/- 18.9 mL/h/kg, and the volume of distribution at steady state was 0.22 +/- 0.01 L/kg. After rectal administration, the plasma concentration of ASA peaked at 5.05 +/- 0.80 microg/mL at 0.33 h, then decreased to undetectable levels by 4 h; the plasma concentration of SA peaked at 17.39 +/- 5.46 microg/mL at 2 h, then decreased to 1.92 +/- 0.25 microg/mL by 36 h. After rectal administration, the AUC for ASA was 439.4 +/- 94.55 microg x min/mL and the bioavailability was 0.17 +/- 0.037. After IG administration, the plasma concentration of ASA peaked at 1.26 +/- 0.10 microg/mL at 0.67 h, then declined to 0.37 +/- 0.37 microg/mL by 36 h; the plasma concentration of SA peaked at 23.90 +/- 4.94 microg/mL at 4 h and decreased to 0.85 +/- 0.31 microg/mL by 36 h. After IG administration, the AUC for ASA was 146.70 +/- 24.90 microg x min/mL and the bioavailability was 0.059 +/- 0.013. Administration of a single rectal dose of ASA of 20 mg/kg to horses results in higher peak plasma ASA concentrations and greater bioavailability than the same dose given IG. Plasma ASA concentrations after rectal administration should be sufficient to inhibit platelet thromboxane production, and doses lower than those suggested for IG administration may be adequate.

Absorption↗
PubMed1978

Plasma concentration of diazepam and N-desmethyldiazepam in children after a single rectal or intramuscular dose of diazepam.

The absorption of diazepam and N-desmethyldiazepam after administration of diazepam solution for parenteral injection per rectum and intramuscularly was studied in 9 children (ages 3--12 years). Rectal administration of diazepam 1 mg/kg led to rapid absorption with plasma levels of 270--320 ng/ml within 5 min, and peak levels of 600--1300 ng/ml 10--60 min after administration. The absorption was comparable to that after intramuscular administration. A second peak in plasma diazepam concentration 6--12 h after dosing was observed in 6 children, which may have been due to mobilization of diazepam from the gastrointestinal mucosa produced by feeding 4 h after administration of the drug. A slowly increasing plasma level of N-desmethyldiazepam was observed during the first 24 h after administration of diazepam.

Child↗
PubMed1982

Bioavailability of diazepam after intravenous, oral and rectal administration in adult epileptic patients.

1 The absorption of single doses of diazepam in six adult epileptic subjects following intravenous, oral and rectal administration were studied in order to evaluate the usefulness of the latter in emergency situations in the adult. 2 Diazepam tablets (Valium, Roche) and rectal solution (Valium solution for intravenous administration) produced similar peak serum concentrations after delays of 15-90 min. 3 Two suppository formulations showed statistically significant differences in absorption characteristics. 4 Serum diazepam levels above 400 ng ml-1 (suggested to be necessary for a satisfactory anticonvulsant effect) were reached in only a few subjects after rectal doses of 10-20 mg of solution, and then usually after a delay of over 2 h.

Administration, Oral↗
PubMed1998

Intrarectal artemisinin derivatives.

The artemisinin derivatives are the most potent antimalarials. They are rapidly absorbed orally, parenterally and intra-rectally. The latter mode of administration is particularly interesting in rural tropics. Preliminary studies have shown that artemisinin and its derivatives artesunate and artemether are effective when given intrarectally. More studies are needed to establish the optimum regimen.

Absorption↗
PubMed1999

Light and electron microscopic study of the hindgut of the ant (Formica nigricans, hymenoptera): II. Structure of the rectum.

The rectum of the ant Formica nigricans is composed of six ovoid rectal papillae inserted into a rectal pouch. The wall of the rectal pouch is made up of a flat epithelium of simple rectal cells lined by cuticle, and surrounded by a circular muscle layer. Each rectal papilla is comprised by a simple columnar epithelium of principal cells facing the lumen, and a simple cuboid epithelium of secondary cells towards the hemolymph; a group of 20-25 slender junctional cells lies laterally between both epithelia enclosing an intrapapillar sinus. The muscle layer of the rectal wall also surrounds the base of the papillae. Principal cells do not exhibit extensive infoldings at the apical and basal plasma membranes. Lateral membranes, in contrast, develop highly folded mitochondria-scalariform junction complexes enclosing very narrow intercellular canaliculi between adjacent cells. These canaliculi open to wider intercellular sinuses that ultimately drain into the intrapapillar sinus at the sites of entry of tracheal cells. The lateral plasma membranes do not link to the apical or basal plasma membrane, thus originating a syncytium throughout the principal cells. The apical plasma membrane of secondary cells shows invaginations in relation with an apical tubulovacuolar system, bearing portasomes to the cytoplasmic side of the membrane. Secondary cells unite by convoluted septate junctions, and basolateral infoldings are also developed. These ultrastructural traits, some of them different from those found in other insects, are discussed and examined in relation to their role in water and solute absorption. A route for rectal transport in F. nigricans is proposed.

Animals↗
PubMed1983

Absorption and excretion of azodisal sodium and its metabolites in man after rectal administration of a single 2-g dose.

The behaviour of azodisal sodium (ADS) and its metabolites after a single 2-g rectal dose was investigated in 10 healthy volunteers. Blood samples were drawn frequently, and urine was collected during intervals of 24 h. The ADS absorption gave a mean peak serum concentration of 2.1 (SD +/- 0.7) microgram/ml. The urinary excretion of ADS was 0.8% of the given dose. After rectal administration 5-aminosalicylic acid (5-ASA) could be detected in the serum only in two of the subjects, with a mean concentration of less than 0.5 microgram/ml. Ac-5-ASA was present in increasing serum concentrations, being 0.93 microgram/ml at 24 h. The mean 24-h urinary excretion of these two metabolites was only 2.7% of the given dose. In another study the azo bond of ADS has been shown to be split by anaerobic and aerobic bacteria. The low absorption of its metabolites indicates that ADS is a suitable molecule for delivering the presumed pharmacologically active moiety, 5-ASA.

Adult↗
PubMed1976

Passive exchanges during water vapour absorption in mealworms (Tenebrio molitor): a new approach to studying the phenomenon.

The weights of single mealworms were continuously recorded at 20 degrees C during exposure to periods of constant humidity and to abrupt changes in atmospheric vapour pressure. Two exchange stages were recognized in each animal. Weight changes were either limited to slow losses, suggesting transpiration through the external cuticle, or showed more rapid humidity-dependent gains as well as losses. Rapid exchanges indicated that water was gained or lost through permeable barriers, from a fluid compartmet of significantly lower vapour pressure than the haemolymph, equivalent to about 90% R.H. Weight gains and losses during humidity changes provided evidence of a significant, passively exchanging fluid compartment located between the exchange surface and absorbing mechanism. Weight changes in faecal pellets following their elimination provide further support for a rectal site of atmospheric absorption.

Animals↗
PubMed2002

Acetaminophen developmental pharmacokinetics in premature neonates and infants: a pooled population analysis.

BACKGROUND: The aim of this study was to describe acetaminophen developmental pharmacokinetics in premature neonates through infancy to suggest age-appropriate dosing regimens. METHODS: A population pharmacokinetic analysis of acetaminophen time-concentration profiles in 283 children (124 aged < or = 6 months) reported in six studies was undertaken using nonlinear mixed-effects models. Neonates and infants were given either single or multiple doses of four different formulations: oral elixir, rectal solution, or triglyceride or capsular suppository. The median postnatal age of children younger than 6 months was 1 day (range, birth to 6 months), median postconception age was 40 weeks (range, 28-64 weeks), and median weight was 3.1 kg (range, 1.2-9.0 kg). RESULTS: Population pharmacokinetic parameter estimates and their variability (percent) for a one-compartment model with first-order input, lag time, and first-order elimination were as follows: volume of distribution, 66.6 l (20%); clearance, 12.5 l/h (44%); standardized to a 70-kg person using allometric "1/4 power" models. The volume of distribution decreased exponentially with a maturation half-life of 11.5 weeks from 109.7 l/70 kg at 28 weeks after conception to 72.9 l/70 kg by 60 weeks. Clearance increased from 28 weeks after conception (0.74 l x h(-1) x 70 kg(-1)) with a maturation half-life of 11.3 weeks to reach 10.8 l x h(-1) x 70 kg(-1) by 60 weeks. The absorption half-life for the oral elixir preparation was 0.21 h (120%) with a lag time of 0.42 h (70%), but absorption was further delayed (2 h) in premature neonates in the first few days of life. Absorption half-life parameters for the triglyceride base and capsule suppositories were 0.80 h (100%) and 1.4 h (57%), respectively. The absorption half-life for the rectal solution was 0.33 h. Absorption lag time was negligible by the rectal route for all three formulations. The bioavailability of the capsule suppository relative to elixir decreased with age from 0.92 (22%) at 28 weeks after conception to 0.86 at 2 yr of age, whereas the triglyceride base decreased from 0.86 (35%) at 28 weeks postconception to 0.5 at 2 yr of age. The relative bioavailability of the rectal solution was 0.66. CONCLUSIONS: A mean steady state target concentration greater than 10 mg/l at trough can be achieved by an oral dose of 25 mg x kg(-1) x d(-1) in premature neonates at 30 weeks' postconception, 45 mg x kg(-1) x d(-1) at 34 weeks' gestation, 60 mg x kg(-1) x d(-1) at term, and 90 mg x kg(-1) x d(-1) at 6 months of age. The relative rectal bioavailability is formulation dependent and decreases with age. Similar concentrations can be achieved with maintenance rectal doses of 25 (capsule suppository) or 30 (triglyceride suppository) mg. kg-1. d-1 in premature neonates at 30 weeks' gestation, increasing to 90 (capsule suppository) or 120 (triglyceride suppository) mg x kg(-1) x d(-1) at 6 months. These regimens may cause hepatotoxicity in some individuals if used for longer than 2-3 days.

Absorption↗
PubMed1987

Absorption and excretion of dilute gastrografin during computed tomography in pseudomembranous colitis.

Since 1955, urinary tract opacification secondary to absorption of orally or rectally administered iodinated contrast material has been recognized. Previously reported cases have involved relatively large volumes of full strength contrast necessary for fluoroscopic examination of the gastrointestinal tract. Our purpose is to report a case of urinary tract opacification in a patient who received a small amount of oral contrast in a dilute solution as preparation for computed tomography examination.

Colon↗
PubMed1982

The effect of metoclopramide on the absorption of tolfenamic acid.

The effect of metoclopramide on the absorption of orally given tolfenamic acid (300 mg) was investigated using rectal metoclopramide hydrochloride (20 mg) pretreatment in a randomized crossover study in eight voluntary migraine patients when headache-free. Tolfenamic acid and metoclopramide serum concentrations were estimated by high-performance liquid chromatograhic (HPLC) methods using UV detection. Metoclopramide given 30 min prior to tolfenamic acid significantly increased serum tolfenamic acid levels at 45 and 60 min after ingestion, compared to the levels obtained with placebo pretreatment. The bioavailability of tolfenamic acid, measured as the area under the serum tolfenamic acid concentration-time curve (AUC0-5 h) and the peak concentration, was not influenced by metoclopramide. The peak concentration of tolfenamic acid was 4.1 +/- 0.9 micrograms/ml (mean +/- s.e.m.), the time peak 1.9 +/- 0.2 h, and the elimination half-life 2.3 +/- 0.5 h calculated from the values without metoclopramide. The peak concentration of metoclopramide was 69 +/- 6.3 ng/ml and the time to peak 118 +/- 29 min. The results suggest that rectal metoclopramide enhances the rate of absorption of tolfenamic acid without changing its bioavailability.

Adult↗