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PubMed2005

Pharmacodynamics and pharmacokinetics of recombinant hirudin via four non-parenteral routes.

One of recombinant hirudin variants, rHV2, a polypeptide used as an anticoagulant agent in clinic, was administered to anesthetized rats via intratracheal, buccal, nasal and rectal routes. Prolongation in clotting time and thrombin time was measured to calculate pharmacological bioavailability. Plasma concentration of rHV2 was determined using a chromogenic thrombin substrate assay and pharmacokinetic parameters were obtained on the basis of a non-compartmental model. Intravenous administration was also performed as the gold standard by which the other routes were compared. Difference in pharmacological bioavailability (P.A.), bioavailability (F) and absorption rate of rHV2 was found for the four non-parenteral routes. The rank order for both P.A. and F was intratracheal>nasal>buccal>rectal. Absorption was more rapid after both intratracheal and rectal administration (tmax approximately 20-40 min), compared with that after nasal and rectal administration. It is evident that the pulmonary route is preferable to other three routes for successful systemic delivery of rHV2.

Absorption↗
PubMed1983

Avoidance of "first-pass" elimination of rectally administered lidocaine in relation to the site of absorption in rats.

The extent of "first-pass" elimination of lidocaine in relation to the site of absorption in the rectum of rats was investigated. Male Wistar rats received lidocaine orally, i.v. or rectally at 4, 2, 1 and at about 0.2 cm from the anus. In all cases 5.0 mg of a tritium-labeled lidocaine solution was administered by zero-order infusion into the rectum. In blood, unchanged lidocaine and urine and feces total radioactivity were measured. Lidocaine was absorbed almost completely in all cases as assessed relative to i.v. administration. The average elimination half-life was about the same for all routes of administration (approximately 27 min). Systemic availability of lidocaine when given by the oral route was 16%; a similar value was found after rectal administration at 4 cm distance from the anus. At 2 cm distance from the anus the mean systemic availability was 21%, at 1 cm, 45% and as closely as possible to the anus, 72%. It is concluded that the degree of avoidance of first-pass elimination of rectally administered lidocaine is very much dependent on the site of drug administration. When the drug is absorbed very closely to the anus, little first-pass elimination occurs.

Administration, Oral↗
PubMed2000

Pharmacokinetics and tissue distribution of amoxicillin in healthy and Salmonella Typhimurium-inoculated pigs.

OBJECTIVE: To determine pharmacokinetics and tissue distribution of amoxicillin in healthy and Salmonella Typhimurium-inoculated pigs. ANIMALS: 12 healthy pigs and 12 S Typhimurium-inoculated pigs. PROCEDURE: Concentration of amoxicillin in tissue was measured by use of high-performance liquid chromatography 4, 8, 12, and 24 hours after IM administration. Pharmacokinetic values of amoxicillin in plasma were assessed by use of a 1-compartment model with first-order absorption. RESULTS: Inoculation caused diarrhea and increased rectal temperature and WBC count. Absorption half-life was shorter in inoculated pigs (0.26 hours) than in healthy pigs (0.71 hours), and inoculated pigs had longer elimination half-life. Distribution ratios in healthy pigs ranged from 0.31 to 0.56 and in inoculated pigs ranged from 0.14 to 0.48. Ratios for distribution to intestinal mucosa ranged from 0.34 to 1.16 in healthy pigs and from 0.22 to 0.36 in inoculated pigs. CONCLUSIONS AND CLINICAL RELEVANCE: Salmonella Typhimurium inoculation altered absorption of amoxicillin from the injection site and prolonged elimination half-life. However, distribution of amoxicillin to intestinal tract tissue was only affected to a minor degree.

Amoxicillin↗
PubMed2003

Amiloride-sensitive epithelial Na+ channel currents in surface cells of rat rectal colon.

Surface cells of the mammalian distal colon are shown to molecularly express the amiloride-sensitive epithelial Na+ channel composed of three homologous subunits (alpha-, beta-, and gamma-ENaC). However, because basic electrophysiological properties of amiloride-sensitive Na+ channels expressed in these cells are largely unknown at the cellular level, functional evidence for the involvement of the subunits in the native channels is incomplete. Using electrophysiological techniques, we have now characterized functional properties of native ENaC in surface cells of rectal colon (RC) of rats fed a normal Na+ diet. Ussing chamber experiments showed that apical amiloride inhibited a basal short-circuit current in mucosal preparation of RC with an apparent half-inhibition constant (Ki) value of 0.20 microM. RT-PCR analysis confirmed the presence of transcripts of alpha-, beta-, and gamma-rENaC in rectal mucosa. Whole cell patch-clamp experiments in surface cells of intact crypts acutely isolated from rectal mucosa identified an inward cationic current, which was inhibited by amiloride with a Ki value of 0.12 microM at a membrane potential of -64 mV, the inhibition being weakly voltage dependent. Conductance ratios of the currents were Li+ (1.8) > Na+ (1) >> K+ ( approximately 0), respectively. Amiloride-sensitive current amplitude was almost the same at 15 or 150 mM extracellular Na+, suggesting a high Na+ affinity for current activation. These results are consistent with the hypothesis that a heterooligomer composed of alpha-, beta-, and gamma-ENaC may be the molecular basis of the native channels, which are responsible for amiloride-sensitive electrogenic Na+ absorption in rat rectal colon.

Amiloride↗
PubMed1993

Cooling effect from absorption of prewarmed irrigating fluid in transurethral prostatic resection.

Thirty patients were studied over 10-min periods in the course of transurethral prostatic resection with measurements of rectal temperature and fluid absorption. Glycine with or without ethanol was used as the irrigant. The changes in the body temperature as reflected in oesophageal and rectal measurements in 5 of the patients were almost identical. Seven of the 30 patients became hyponatraemic and absorbed an average of 1328 ml of glycine solution. They had a significantly greater drop in rectal temperature than patients with little or no fluid absorption. This cooling effect occurred despite prewarming of the irrigant medium to 37 degrees C, which can be explained by a decrease in fluid temperature when the bag is being emptied. It was concluded that absorption of irrigating fluid is a mechanism that promotes heat loss during transurethral operations.

Absorption↗
PubMed2000

Effect of dehydration on gastrointestinal function at rest and during exercise in humans.

Dehydration leads to the aggravation of gastrointestinal (GI) complaints during exercise. The aim of this study was to examine the effect of dehydration on various GI parameters during strenuous exercise. Ten healthy well-trained men were investigated in dehydrated and in euhydrated conditions. Dehydration took place before the experiments using a dehydration regimen in a sauna leading to a 3% loss of body mass. Each experiment consisted of 1 h pre-exercise rest, 1.5 h cycling at 70% maximal exercise intensity, and 3.5 h post-exercise rest. During cycling, liquid gastric emptying (GE), orocaecal transit time (OCTT) and intestinal permeability and glucose absorption were measured. The GI-symptoms were scored using a questionnaire. Body temperature, plasma volume and vasopressin were measured before and after cycling. The GE was significantly slower during dehydration [median time to peak 13C enrichment in the breath sample (13C-TTP) 23.6 min, range 13.7-50.0 min, P = 0.02] than in the control situation (median 13C-TTP 17.1 min, range 9.8-38.4 min). The OCTT was unchanged (median 173 min, range 98-263 min compared to median 128 min, range 98-195 min, P = 0.18). Dehydration did not change intestinal permeability, glucose absorption, plasma volume, rectal temperature or plasma vasopressin concentration. In the dehydration experiment, exercise induced a significant increase in nausea (P = 0.01) and epigastric cramps (P = 0.05), in contrast to the control situation. In both experiments, exercise led to a significant increase in rectal temperature and plasma vasopressin concentration, and a significant decrease in plasma volume. The increase in plasma vasopressin concentration was significantly higher in the dehydration experiment (P = 0.015). No significant differences in either the post-exercise rectal temperatures or in plasma volumes was observed. The difference in GE between the two experiments was significantly correlated with the difference in nausea score (r = 0.87, P = 0.002). We concluded that dehydration leads to a delayed GE but not to differences in OCTT, intestinal permeability or glucose uptake during intense cycling. The delay in GE is significantly associated with an increase in exercise-induced nausea.

Absorption↗
PubMed1998

An approach for dose finding of drugs in infants: sedation by midazolam studied using the continual reassessment method.

AIMS: No drug has been demonstrated to provide simultaneously appropriate sedation, safety and lack of disturbance of the measured parameters during cardiac catheterization in infants. The objective of this study was to estimate the dose of midazolam, administered rectally, that would provide a 90% probability of adequate sedation in infants during cardiac catheterization. A sedation score > or =4 (six-point scale) 30 to 60 min after dosing was rated as a success. METHODS: A double-blind, continual reassessment method using a Bayesian approach has been used. Sixteen infants were administered a single midazolam dose, within a 0.1 to 0.6 mg kg(-1) dose range. RESULTS: Consecutive failures led to allocation of the highest dose to 15 out of 16 patients. The final estimated probability of failure of the 0.6 mg kg(-1) dose was 81% (95% CI: 78.5 to 84%). The time to reach a score > or =4 was longer than expected and the median duration-time at score > or =4 was shorter (15 min) than expected. CONCLUSIONS: Delayed absorption and low rectal bioavailability may explain these data. Higher doses or different routes of administration may lead to the expected sedation, but the safety of doses higher than 0.6 mg kg(-1) administered rectally has not been evaluated. The therapeutic strategy for sedation of this category of infants in the hospital has now been changed based on the present results in that rectal midazolam has been abandoned in this indication.

Administration, Rectal↗
PubMedDate not supplied

Relative bioavailability of rectally administered carbamazepine suspension in humans.

The relative bioavailability of an investigational carbamazepine suspension was studied following rectal administration in human volunteers. Carbamazepine, in doses of approximately 6 mg/kg, was given to nine men. The routes of administration were oral tablet, oral suspension, and rectal suspension. There was no significant difference (p greater than 0.05) in total absorption, maximum serum concentration, and time to achieve maximum serum concentration between the orally-administered tablet and the rectally administered suspension. Orally administered suspension was absorbed more quickly and completely. All volunteers complained of a strong defecatory urge after the suspension was given rectally. The slow absorption after rectal administration precludes the use of this route in status epilepticus; however, it may be a satisfactory alternative for maintenance therapy when administration by the oral route is not possible.

Adult↗
PubMed2005

Posterior pelvic floor compartment disorders.

Posterior pelvic floor compartment disorders generally refer to functional anorectal disturbances that by definition are symptom-based rather than anatomical defect-based and have a significant impact on quality of life. Symptoms attributed to the posterior compartment are often non-specific and associated with structural, neuromuscular and functional defects giving rise to symptoms of prolapse, pelvic pressure, faecal incontinence, stool trapping and constipation. They may range from mild to incapacitating and occur in varying combinations. While symptoms of constipation and incontinence may conceptually represent the opposing extremes of normal anorectal function, the dynamic interrelationships between the different pathophysiological mechanisms involved in the development of these disorders suggest a more complex explanation. Faecal continence and defecation are dependent on several neurological and anatomical factors that involve coordinated physiological processes, including intestinal transit and absorption, colonic transit, rectal compliance, anorectal sensation and continence mechanism. However, it is well recognized that pelvic floor symptoms originating from one compartment do not imply absent pathology in another compartment. Furthermore, symptoms associated with one disorder (such as constipation related to functional obstructed defecation) can be causative in the sequential development of other pelvic floor disorders, such as a urogenital prolapse syndrome, that may further exacerbate symptoms. In addition, it has been found that treatment that corrects one problem may improve, worsen or even predispose to other symptoms from another compartment. Consequently, while the concept of global pelvic floor dysfunction has emerged, the traditional single speciality referral and evaluation of pelvic floor problems continues to foster potentially segregated management strategies that can overlook the relevance of concomitant symptomatology. The evaluation and treatment of posterior pelvic compartment disorders needs to assume an individualized but multidisciplinary therapeutic approach. Given the variation in surgical approaches described to correct anatomical integrity of posterior pelvic compartment deficits, the consensus on optimal management has yet to be achieved. Therefore, it is critical that outcome measures following surgery are clearly defined. Treatment is to a great extent dictated to by functional severity and the impact that symptoms have on quality of life. Long-term follow-up should ensure that the potential for complications is minimized and satisfactory bowel, bladder and sexual function is maintained.

Anus Diseases↗
PubMed1987

Bioavailability of rectally administered carbamazepine mixture.

The relative bioavailability of carbamazepine mixture was studied after oral and rectal administration to healthy subjects. The absorption was significantly slower after the rectal than after the oral route but the total bioavailability was similar provided the mixture was not defaecated within 2 h of administration. We conclude that carbamazepine can be administered rectally, e.g. to postoperative patients in doses corresponding with oral doses.

Administration, Rectal↗
PubMed2004

Regulation of intermediary metabolism and water balance of insects by neuropeptides.

Neuropeptides regulate all important physiological, developmental, and behavioral processes in insects. Here, I review two major physiological events that are hormonally controlled, namely intermediary metabolism and ion and water transport. Peptides belonging to the family of adipokinetic hormones (AKHs) increase hemolymph carbohydrates, lipids, and proline by activating the enzyme glycogen phosphorylase or lipase in the fat body. Moreover, these pleiotropic and multifunctional peptides inhibit protein-, lipid-, and RNA synthesis, and stimulate the frequency of contraction of certain muscles. Diuretic hormones that are related to the vertebrate corticotropin-releasing factor (CRF-related DHs) or belong to the family of kinins (which also have a myotropic action) or the cardioacceleratory peptides (CAPs), which increase the frequency of the heartbeat, all stimulate the secretion of fluid in Malpighian tubules (MTs) in vitro. Only a few true antidiuretic hormones are known: those from mealworms that inhibit the fluid transport in MTs in vitro, probably neuroparsins that stimulate water absorption by everted rectal sacs in vitro, and the desert locust's ion-transport peptide (ITP). Biosynthesis, release, receptors, mode of action, inactivation, structure-activity studies, and biological functions are discussed for the various peptides.

Amino Acid Sequence↗
PubMed1989

Rubidium (Rb) treatment of rats: biological effects and implications for psychiatry.

Experiments were carried out on rats in order to find out the implications for psychiatry of the basic biological effects of rubidium (Rb). The forced swimming test (FST), used to evaluate the effects on rats of treatment with Rb, was conducted after 1 or 3 mEq/kg Rb was given chronically or subacutely. The weight of rats treated with 1 or 3 mEq/kg Rb, once daily, was observed daily for two weeks. Rb levels in the blood and brain of rats treated with Rb chronically or subacutely were determined by atomic absorption spectrophotometry. The rectal temperature was observed at 30, 60, 90, 120, 180, and 240 min after injections of 1 or 3 mEq/kg Rb. The increase in the mean body weight of treated rats was almost the same as that of the control. The rectal temperature in rats treated with Rb showed a hyperthermic response. With both the 1 and 3 mEq/kg Rb treatments, Rb levels in the brains were significantly higher in the chronic experiments than in the subacute experiments. The experiments conducted to determine the effect of chronic and subacute treatment of Rb are hereafter termed 'chronic experiment' and 'subacute experiment' respectively. Almost the same significant difference was also observed in the Rb levels in the blood. In the FST, a decrease in the mean immobility time was not observed in either the subacute or the chronic experiments. Thus, antidepressant effects, as judged from the FST, were not observed although Rb did actually accumulate in both brain and blood.

Animals↗
PubMed1981

Pharmacokinetics of nitroimidazoles. Spectrum of adverse reactions.

A short review is given of the pharmacokinetic characteristics and side effects of the nitroimidazoles: metronidazole, tinidazole and ornidazole. The drugs are well absorbed from the gastrointestinal tract, maximum plasma levels generally being obtained 1 to 4 h after oral intake. Metronidazole has been shown to be absorbed after rectal administration; vaginal absorption is documented for all three drugs. The nitroimidazoles are widely distributed in the body, cross the placenta and appear in breast milk. Therapeutically effective concentrations of e.g. metronidazole have been demonstrated in e.g. the central nervous system, middle ear discharges, bile, peritoneal fluid, and fluids and tissues of the female genital tract. The binding to plasma proteins is less than 20%. Available data suggest that the elimination half-lives of these drugs differ, being 7-8 h for metronidazole, about 12 h for tinidazole and 14-15 h for ornidazole. Both metronidazole and ornidazole, but not tinidazole, seem to be extensively metabolized before elimination. The nature and frequency of adverse reactions to this drug include encephalopathy in a few patients treated with doses between 5 and 10 g daily as an adjunct to radiotherapy, and peripheral neuropathy observed in patients treated for prolonged periods with high doses. Among the common side effects of the nitroimidazoles are symptoms from the gastrointestinal tract such as nausea, anorexia, vomiting and metallic or bitter taste. Dizziness, ataxia and headache have been reported. When given together with alcohol, a disulfiram-like intolerance reaction can be obtained.

Humans↗
PubMed1989

[Rectal injury caused by a broken thermometer. Risks related to mercury].

This is a case of local mercury absorption caused by accidental rectal perforation during monitoring of temperature. This complication is only reported in cases of subcutaneous injury by a broken thermometer. Treatment necessitates complete excision of mercury deposits. When mercury remains, a clinical and biochemical follow-up is necessary but indication for chelation therapy is exceptional.

Foreign Bodies↗