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PubMed1980

Pharmaceutical studies of polyacrylic acid aqueous gel bases: absorption of insulin from polyacrylic acid aqueous gel bases following rectal administration in alloxan diabetic rats and rabbits.

The effect of gel preparation on the rate of absorption of a rectally administered insulin which was suspended in a polyacrylic acid aqueous gel base (0.1%, pH 6.5) was investigated in the alloxan diabetic rats and rabbits. The preparation was administered into the in situ rectal loop in rats or infused directly into the rectum in rabbits, and the change in the blood glucose level and plasma insulin value was taken as a measure to evaluate the rate of rectal absorption of insulin. The blood glucose lowering effect in both rats and rabbits was dose-dependent, namely, a slight effect was observed at 1 IU/kg followed by a significant effect with 3 and 5 IU/kg, and a sharp hypoglycemic effect was recorded with 10 IU/kg which lasted for 5 hr. The plasma insulin level exhibited a rapid increase at 30 minutes after the dosing of the insulin by the polyacrylic acid aqueous gel base. However, the plasma level quickly diminished in 1 hr. Contrary to our expectation, an addition of a non-ionic surfactant such as Tween 80 under pH 4--8 did not show further enhancement of the absorption. In an attempt to simulate a clinical condition in which insulin was given after a meal, the insulin gel was administered into the rectal loop in diabetic rats following the i.v. injection of glucose. A satisfactory result was obtained in which 5 IU/kg dose was able to suppress a rise in the blood glucose after the glucose loading.

Acrylic Resins↗
PubMed2003

Pharmacokinetics and adverse-effect profile of rectally administered misoprostol in the third stage of labor.

OBJECTIVE: To characterize the pharmacokinetics and adverse-effect profile of rectally administered misoprostol. METHODS: To assess absorption of rectally administered misoprostol, 20 women were randomized to receive misoprostol 600 microg by either oral or rectal administration after delivery. Blood samples were obtained at 0, 7.5, 15, 30, 45, 60, 90, 120, and 240 minutes and analyzed for serum concentrations of misoprostol free acid by enzyme-linked immunosorbent assay. Additionally, 275 women were randomized to receive rectal 400 microg, rectal 600 microg, or oral 600 microg misoprostol after delivery. Self-assessment questionnaires were used to ascertain the adverse-effect profiles. RESULTS: Misoprostol tablets are absorbed rectally even though they are formulated for oral use. The area under the curve (integral of concentration and time graph) for rectal misoprostol was higher by 121 pg.h/mL (95% confidence interval [CI] -4.2, 246.2) than for oral misoprostol. The rectal route group had a mean maximum serum concentration 144 pg/mL lower than that for the oral route (95% CI 63, 225). This maximum was achieved on average 23 minutes later than in the oral group (95% CI 10, 35). Shivering was reported by 76% of the patients in the oral 600-microg arm, 56% of the patients in the rectal 400-microg arm, and 54% of the patients in the rectal 600-microg arm. The relative risk of shivering in the combined rectal groups is 73% that of the oral group (95% CI 61%, 86%). Severe shivering reported by patients was significantly reduced, by 72%, in rectal groups compared with the oral group (95% CI 60%, 81%). CONCLUSION: Misoprostol administered rectally is associated with lower peak levels and a reduction in adverse effects compared with the oral route. Increasing rectal doses may achieve higher efficacy without reducing the acceptability of the treatment.

Administration, Oral↗
PubMed1984

Rectal administration of insulin.

According to recent statistics for the time span 1951-1970, the mortality ratio of diabetics to non-diabetics was 335% (46). For those diabetics who were younger than 15 years when entering the study, the mortality ratio was 1127%, with a mean life expectancy of another 32 years, as compared to 59 years for non-diabetics. Among the major causes of disablement and early death are ischemic heart disease, retinopathy, nephropathy, peripheral vascular disease and neuropathy. In spite of newer, more potent and highly purified insulins, development of human insulin, change of once-daily injection to twice-daily insulin therapy (47), and the introduction of portable insulin infusion pumps, diabetes is still a high-risk disease, far from being controlled. Considering that the present mode of insulin administration is by the subcutaneous route by which the insulin is presented to the body in a nonphysiological manner, because the insulin is peripherally administered to the systemic circulation instead of portally, new therapeutic ways for insulin administration are worth study. During the past years, considerable interest has arisen in the rectal route of administration. Based on a physiological-kinetic model presented in this paper, utilization of the first-pass effect inherent to the rectal anatomy offers a physiological insulin input via the rectal route of administration. A review on the present state of rectal insulin administration is given, and experimental data from our laboratories are presented. The usefulness of sorption promoters on rectal insulin absorption is discussed. The "effectiveness" of rectal insulin preparations is suggested to be evaluated by four criteria: the pharmacological availability via the area under the % glucose reduction-time profile, the maximum glucose concentration reduction, Cmax, the time to reach the maximum reduction, tmax, and the mean residence time for glucose reduction, MRT.

Animals↗
PubMed1999

Lack of absorption of didanosine after rectal administration in human immunodeficiency virus-infected patients.

The feasibility of rectal administration of didanosine (DDI) was studied in six human immunodeficiency virus-infected patients. After oral intake of a DDI solution (100 mg/m2 of body surface area) combined with an antacid (Maalox), pharmacokinetic parametric values were in accordance with previously published data; the mean +/- standard deviation for terminal half-life was 59.5 +/- 15.0 min, that for peak concentration was 5.2 +/- 3.9 mumol/liter, and that for the area under the time-concentration curve (AUC) was 494 +/- 412 min.mumol/liter. After rectal administration of a similarly prepared DDI solution (100 mg/m2 of body surface area), plasma DDI levels were below the detection limit (0.1 mumol/liter) at all time points in five of the six patients, and in the remaining patient the AUC after rectal application was only 5% of that after oral administration. We conclude that oral administration of DDI cannot be easily replaced by rectal application.

Administration, Rectal↗
PubMedDate not supplied

The beneficial acclimation hypothesis versus acclimation of specific traits: physiological change in water-stressed Manduca sexta caterpillars.

Do organisms make beneficial physiological adjustments in response to environmental change? We examined this question by measuring the effects of short-term (12-36 h) and long-term (larval lifetime) hydric stress on the tobacco hornworm, Manduca sexta. Larvae were reared from the first instar on low-water (69%) or high-water (80%) artificial diets and then transferred early in the fifth instar to the same or opposite diet (2x2 design). Within the subsequent 36 h, we measured 24-h growth rates and three primary determinants of the water budget: water gain via consumption and water loss via evaporation and defecation. Larvae preexposed to low-water diet grew less rapidly on low-water diet than those switched acutely to low-water diet from high-water diet, showing that larvae preexposed to a particular environment do not necessarily acclimate beneficially to that environment. Our data on water fluxes to and from larvae, however, strongly suggest that water-stressed larvae did make beneficial physiological adjustments. Larvae responded to short-term hydric stress by minimizing rates of water excretion, primarily by increasing rates of rectal water absorption. Larvae responded to chronic water stress by significantly reducing rates of evaporative water loss; they also showed additional reductions in fecal water excretion, but these decreases were due to lowered consumption and not to further increases in rate of rectal water absorption. This mismatch between maladaptive acclimation of organismal performance and beneficial adjustment of suborganismal traits can be reconciled by recognizing that organismal physiology is hierarchical: fitness-related performance traits represent the aggregate outcome of numerous, more mechanistic physiological traits. Although chronic exposure to an environment may depress the aggregate effect of these mechanistic traits on performance, organisms are not precluded from making beneficial adjustments to individual traits contributing to performance.

Acclimatization↗
PubMed1994

Improvement of the rectal bioavailability of latamoxef sodium by adjuvants following administration of a suppository.

The absorption of an antibiotic, latamoxef sodium (LMOX), following the rectal administration of a suppository containing adjuvants was investigated. A lipophilic base (Witepsol H15) was used. The rectal absorption of LMOX following the administration of a suppository without adjuvants was very low. Diclofenac sodium (DF) was used as an absorption promoter; it enhances rectal membrane permeability. The blood level of LMOX following the addition of DF(10 mg) to the base was increased only about 1.3-fold compared with that achieved with LMOX alone (difference not significant); even with a higher dose of DF, the absorption of LMOX was not sufficient. The release rate of LMOX from the base was slow. When Tween 80, a non-ionic surfactant, was added to improve the release rate of LMOX, the rate was sufficiently increased. The rectal absorption of LMOX on the addition of both Tween 80 and DF was markedly increased compared to that achieved with LMOX alone or with DF. These results indicate that the rectal absorption of LMOX after administration by a suppository was sufficiently improved by enhancing both the release rate from the base and the membrane permeability of the rectum. Lymphatic uptake and blood levels of LMOX were also investigated after the rectal administration of the LMOX preparation containing both Tween 80 and DF; the lymphatic uptake of LMOX was significantly enhanced compared with the LMOX preparation in which only DF was used as an adjuvant. The mechanism whereby adjuvants lead to the absorption of a non-absorbable drug, and the subsequent drug transportation routes through the membrane are discussed.

Adjuvants, Pharmaceutic↗
PubMed1998

Studies of drug delivery systems for a therapeutic agent used in osteoporosis. I. Pharmacodynamics (hypocalcemic effect) of elcatonin in rabbits following rectal administration of hollow-type suppositories containing elcatonin.

In this study, we developed a new hollow-type suppository containing elcatonin ((Asu1,7)-eel calcitonin, ECT), a synthetic derivative of eel calcitonin, which produces hypocalcemia, as a pharmaceutical preparation for self administration, to be used instead of parenteral injections for patients with osteoporosis. The absorption of ECT from the rectal mucous membrane was evaluated by observation of the decrease in serum calcium (Ca) concentrations following rectal administration in rabbits. ECT was efficiently absorbed from the rectum and effectively decreased serum Ca concentrations. The data of the area under the percent decrease in serum Ca concentration (deltaCa%)-time curve (deltaCa%-AUC), assumed to be an index of the pharmacodynamics (pharmacological effect) of ECT, indicated that similar hypocalcemic effects were obtained following rectal and intravenous administrations of ECT. In regard to the effect of coadministration of other compounds on rectal absorption of ECT, no significant difference in the deltaCa%-AUC between rectal ECT administration with or without nafamostat mesilate (a protease inhibitor) was observed. However, the coadministration of ECT with cytochalasin B or monensin (endocytosis inhibitors) significantly decreased the deltaCa%-AUC, indicating that rectal ECT absorption is probably inhibited by endocytosis inhibitors. On the other hand, it was found that sodium decanoate, a medium-chain fatty acid (sodium salt), significantly enhanced the rectal absorption of ECT. We conclude that this ECT hollow-type suppository offers promise as a new method for the administration of ECT.

Absorption↗
PubMed1982

Absorption and bioavailability of rectally administered morphine in women.

21 healthy women undergoing gynaecological operations received rectal premedication with morphine 0.3 mg/kg body weight. Plasma concentrations of morphine were followed for 4 h by a GC/MS technique. In most patients the peak plasma concentration was reached after 30 min; the mean peak plasma level of morphine was 18 ng/ml (range 8.5-57 ng/ml). The bioavailability of rectal morphine was determined in 6 patients, who received an i.m. injection of morphine at a second operation. The mean bioavailability of rectal morphine was 31% (range 12%-61%). None of the patients showed any clinical sign of respiratory depression, and there was no increase in end-tidal carbon dioxide tension measured in 5 patients operated under spinal block.

Adult↗
PubMed1986

[The effect of rectal pH values on the absorption of methohexital].

The factors underlying the unpredictability of the pharmacokinetics of rectally administered methohexitone remain unclear. The "pH partition hypothesis" offers an explanation. We investigated six children with rectal pH values ranging from 7.5 to 9.8, who were given 25 mg/kg methohexitone 10% via the rectal route under general anaesthesia. Blood samples were taken at zero, 3, 5, 7, 10, 15, 20, 30, 40, 60, 90 and 120 min; rectal pH was measured at zero and 1 min. The methohexitone plasma levels reached a maximum (Cmax) of 2.63 micrograms/ml (median) after 17.5 min (median). The elimination half-life ranged from 37 to 218 min. No positive correlation between lower pH and better resorption (AUC and Cmax) was found. The resorption kinetics of rectally administered methohexitone cannot be explained by its electrochemical properties alone.

Anesthesia, Rectal↗
PubMed1983

A pathophysiological study of the intestinal manifestations of a vasoactive intestinal peptide, calcitonin, and catecholamine-secreting tumour.

A three year old girl with severe watery diarrhoea and a vasoactive intestinal peptide, calcitonin, and catecholamine-secreting supra-renal ganglioneuroblastoma is reported. Steady-state perfusion studies showed the jejunum to be in a net secretory state with respect to water, sodium, and chloride at low concentrations (2 mmol/l) of glucose whereas higher concentrations (56 mmol/l) reversed secretion to absorption; transmural rectal potential difference was increased (lumen negative); Na+ absorption by the rectum was impaired and secretion of potassium and bicarbonate excessive. Motility studies showed prolonged, slowly propagated migrating motor complexes with abnormal runs of non-propagated contractions in the fasting state. During perfusion with glucose, no postprandial activity occurred. These results suggest that diarrhoea results from small intestinal secretion with impaired colonic function and that tumour products may have a direct effect on intestinal motility.

Adrenal Gland Neoplasms↗
PubMed1981

Orally and rectally administered streptokinase. Investigation of its absorption and activity.

The absorption and activity of orally and rectally administered streptokinase was investigated. No difference was found between the levels of plasminogen activators and antistreptokinase antibodies before and after oral or rectal administration of streptokinase-streptodornase (Varidase), nor was there any difference in the hematoma resorption times between patients treated with oral streptokinase and a control group. We found no evidence of streptokinase absorption or increased fibrinolytic activity in plasma after oral or rectal administration in our patients.

Administration, Oral↗