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At least 685 records · Page 38Linked to original sources
PubMed1982

Vaginal absorption of a potent luteinizing hormone-releasing hormone analog (leuprolide) in rats I: absorption by various routes and absorption enhancement.

The absorption of a potent luteinizing hormone-releasing hormone analog (leuprolide) through different routes was evaluated by determining the ovulation-inducing activity in diestrous rats. Vaginal administration showed the greatest potency among nonparenteral routes and was followed successively by rectal, nasal, and oral administration. Mixed micellar solution with monoolein-bile acids improved the intestinal absorption of leuprolide, and nasal absorption was enhanced by adding sodium glycocholate, surfactin, or polyoxyethylene 9 lauryl ether, but these bioavailabilities were still insufficient. The vaginal absorption was enhanced by organic acids: citric, succinic, tartaric, and glycocholic; the absolute bioavailability increased to approximately 20%. The vaginal absorption from jellies, as practical dosage forms, yielded sufficient activity of leuprolide, but absorption was slightly reduced with highly polar polymers or with higher concentrations of polymers. It was concluded that vaginal administration of leuprolide can be a rational dosage method for a long-term antitumor therapy.

Absorption↗
PubMed1986

Enkephalin hydrolysis in homogenates of various absorptive mucosae of the albino rabbit: similarities in rates and involvement of aminopeptidases.

The systemic delivery of peptides and proteins from the nasal, rectal, vaginal, and buccal mucosae has been the subject of active investigation. The objective of this study was to determine the pathway and rate of hydrolysis of methionine enkephalin (TGGPM), leucine enkephalin (TGGPL), and [D-Ala2] met-enkephalinamide (TAGPM) in homogenates of these non-oral mucosae relative to the ileal mucosa. Aminopeptidases appeared to contribute over 85% to the hydrolysis of TGGPM and TGGPL, while dipeptidyl peptidase and dipeptidyl carboxypeptidase contributed much less. Overall, TGGPM was somewhat more susceptible to hydrolysis than TGGPL but was 10 times more so than TAGPM. These enkephalins were most rapidly hydrolyzed in the rectal and buccal homogenates, followed by the nasal and then the vaginal homogenates, but the differences in hydrolytic rates were small. Indeed, these rates did not differ substantially from the ileal mucosa, suggesting that the same enzymatic barrier to enkephalin absorption possibly exists in both the oral and the non-oral mucosae.

Aminopeptidases↗
PubMedDate not supplied

Effects of calcium concentration, acetate, and propionate on calcium absorption in the human distal colon.

Previous studies have shown that the short-chain fatty acids acetate (Ac) and propionate (Pr) enhance the absorption of calcium (Ca) in the rectum and distal colon of humans, with Pr being more effective than Ac. To investigate the effect of Ac and Pr on the kinetics of Ca absorption from the human rectum and distal colon, six healthy subjects were studied. Solutions containing various concentrations of CaCl2.H2O with 56.3 mmol/L Ac, Pr, or NaCl were rectally infused to each subject. Rectal fluid was sampled at the end of the infusion (0 min), and 30 min later colonic contents were collected. Ca absorption for all treatments increased linearly with Ca concentration. For Ca + NaCl, the slope of regression line was 62 mumol.mmol-1.L Ca. With Ac + Ca, the slope of Ca absorption increased significantly to 113 mumol.mmol-1.L Ca, and with Pr + Ca, the slope increased to 159 mumol.mmol-1.L (P = 0.043 versus Ac + Ca) Ac and Pr absorption were increased by Ca. The data suggest that, over a physiologic range of Ca concentration, in the absence or presence of Ac and Pr, Ca is absorbed in the human rectum and distal colon by a non-saturable diffusion process, and that Ca absorption is enhanced by Ac and Pr. The data also suggest that both Ac and Pr absorption is stimulated by Ca.

Acetic Acid↗
PubMed1983

Rectal ketamine for induction of anaesthesia in children.

Rectal premedication with atropine and diazepam and rectal induction of anaesthesia with ketamine have been used in 30 healthy children undergoing minor surgery. The anticholinergic and sedative effects of the premedication were satisfactory. Induction of anaesthesia was smooth with no adverse circulatory or respiratory effects. No psychotomimetic side-effects were seen, and analgesia persisted into the recovery period. Plasma concentrations of ketamine and norketamine were measured in eight children and revealed a pharmacokinetic pattern indicating comparatively low bioavailability probably due to incomplete absorption from the rectum and a high 'first-pass' metabolism. The technique of rectal administration of ketamine needs further pharmacokinetic evaluation before it can be generally recommended.

Anesthesia, Rectal↗
PubMed1996

Effect of acetate and propionate on calcium absorption from the rectum and distal colon of humans.

To determine the effects of acetate and propionate on calcium absorption from the human distal colon and rectum, six healthy human subjects were given rectal infusions containing 50 mmol CaCl2/L on four separate occasions. Addition of 56.3 mmol acetate/L, 18.7 mmol propionate/L, or acetate and propionate together increased calcium disappearance (expressed as the change in the ratio of calcium to polyethylene glycol) from -5.5 +/- 1.4 to -22.6 +/- 2.8, -23.2 +/- 3.2, and -19.7 +/- 4.6, respectively; P < 0.05. To determine the effects of different acetate and propionate concentrations, six different subjects were studied further. The effects of 18.7 or 56.3 mmol acetate/L on calcium absorption were the same as those of 18.7 mmol propionate/L (-15.7 +/- 1.4), and less than those of 56.3 mmol propionate/L (-20.3 +/- 2.4, P < 0.05). We conclude that both acetate and propionate enhance calcium absorption from the human distal colon, but that propionate has a greater effect at higher concentrations. Further studies are needed to determine the mechanism of calcium absorption from the colon.

Acetates↗
PubMed1975

Bioavailability of aspirin from commercial suppositories.

A comparison of the bioavailability of salicylate from five brands of commercially available aspirin rectal suppositories in an adult panel is presented. All brands show slow absorption compared to oral administration of the drug in tablet form. At best, about 40% of the dose (on the average) was absorbed when retention time in the bowel was limited to 2 hr. However, four out of the five brands give substantially lower absorption rates so that only about 20% of the aspirin is available.

Adult↗
PubMed1986

Piroxicam capsules versus suppositories: a pharmacokinetic and clinical trial.

15 patients with rheumatoid arthritis or osteoarthritis received a single dose (20 mg) piroxicam (Felden) as suppository. Serum piroxicam concentrations were assayed by fluorometry 1, 2, 4, and 8 h after the installation of the suppository, the mean values being 1.3, 1.9, 1.8, and 1.8 mg/l, respectively. Then the patients continued on oral piroxicam 20 mg daily for maximum 3 weeks, and serum piroxicam levels (mean 6.3 mg/l) were checked at the end of this period. Nine patients then continued on piroxicam suppositories 20 mg daily for one week, and serum piroxicam levels (mean 4.5 mg/l) were again assayed at the end of this maintenance. Pain at rest, pain on motion, and joint movement restriction were scored on day 1, after oral maintenance, and after rectal maintenance. Reduced scores were found with time, but the only statistically significant effect was in the overall subjective pain relief measured after oral maintenance. Rectal irritation was recorded in one patient. It is concluded that a) absorption of piroxicam from suppository was adequate, b) it was possible to maintain adequate serum piroxicam levels by repeated administration of suppository for one week, and c) the gastrointestinal toleration was acceptable in these patients selected for showing poor tolerance towards other nonsteroidal antiinflammatories.

Aged↗
PubMed1997

Double-blind, randomized study of the effect of cisapride on gastric emptying in critically ill patients.

OBJECTIVES: To investigate the absorption of the gastrokinetic drug, cisapride, and effect of cisapride on gastric emptying in critically ill patients; and to assess the usefulness of clinical signs of gastric emptying. DESIGN: Prospective, randomized, controlled study. SETTING: Medical/surgical/trauma intensive care unit (ICU) in a university hospital. PATIENTS: Twenty-seven consecutively enrolled patients, aged 18 to 65 yrs, with normal hepatic and renal biochemistry who were not receiving enteral nutrition and who had no contraindications to enteral nutrition. These patients were expected to stay in the ICU for at least 4 days. INTERVENTIONS: Patients were randomized to receive either placebo or rectal cisapride, 60 mg initially followed by two doses of 30 mg at 8-hr intervals. MEASUREMENTS AND MAIN RESULTS: Gastric emptying was estimated, using acetaminophen absorption on day 1 of the study. Placebo or cisapride was administered and a second acetaminophen absorption test for gastric emptying was carried out on day 2,24 hrs after the first test. Four patients were excluded because of incomplete data. Statistical analysis was performed, using the area under the acetaminophen absorption curve from 0 to 60 mins as the primary measure of gastric emptying. There was no significant change in the area under the acetaminophen absorption curve from 0 to 60 mins from day 1 to day 2 in patients who received placebo or cisapride. Using the combination of the time to maximum acetaminophen concentration (< or = 30 mins) with a maximum concentration (> 12 mg/L) to define "normal" emptying, on day 1, four of the 11 placebo patients had the "normal" gastric emptying, and by day 2, five patients fulfilled this criterion. Before administration of cisapride, four of the 12 patients fulfilled this criterion, whereas nine fulfilled the criterion after receiving cisapride. There was a large variation in gastric emptying from day 1 to day 2; a power calculation suggests that approximately 150 patients would have to be studied to determine the effect of cisapride. There was no correlation between gastric emptying and the volume of gastric aspirate or the presence of bowel sounds. Plasma cisapride concentrations 4 hrs after the third dose, during the second acetaminophen absorption test, averaged 53 ng/mL (range 20 to 111). CONCLUSIONS: Rectal cisapride in the dose given achieved average plasma concentrations similar to those concentrations achieved in healthy subjects after 30 mg of cisapride rectally. There is a large variation in gastric emptying from one day to the next and large numbers of patients are required to determine if cisapride administration improves early gastric emptying in critically ill patients. The volume of gastric aspirate and the presence of bowel sounds do not correlate with gastric emptying.

Administration, Rectal↗
PubMed1984

Mechanism of the antidiarrheal effect of loperamide.

To determine whether the antidiarrheal effect of loperamide is due to an effect on intestinal motor function or to an acceleration of the rate of absorption by the intestine (as has been suggested recently), we studied absorption during experimental diarrhea produced by the rapid intragastric infusion of electrolyte solution. In studies in which a 2700-ml bolus of electrolyte solution was infused into the stomach over 90 min, loperamide delayed the appearance of rectal effluent in each of 5 subjects and decreased the volume of rectal effluent from 1090 +/- 118 to 770 +/- 73 ml (p = 0.05). When intragastric infusion was continued for 5 h, producing steady-state total gut perfusion, the volume of effluent produced per unit time and the concentration of a nonabsorbable polyethylene glycol marker in rectal effluent was not different with or without loperamide, indicating that loperamide did not alter the rate of absorption by intestinal mucosal cells. Loperamide also had no effect during steady-state perfusion when absorption rates were reduced by intravenous infusion of vasoactive intestinal polypeptide. Loperamide did substantially increase the intraluminal volume of the total gut, from 985 +/- 131 to 1764 +/- 195 ml (p less than 0.02). These results suggest that loperamide exerts its antidiarrheal effect by a change in the motor function of the intestine, which results in increased capacitance of the gut and a delay in the passage of fluid through the intestine. This change in motor function, rather than a change in the rate of absorption by intestinal mucosal cells, is responsible for the antidiarrheal effect of loperamide in our experimental diarrhea model.

Adult↗
PubMed1985

A noninvasive method for monitoring intestinal ischemia: changes in the pulmonary clearance of helium instilled into the colon as an index of colonic blood flow.

To evaluate the concept that changes in colonic blood flow will predictably alter the absorption of colonic gas, we measured the pulmonary clearance rate of helium (CHe) which was instilled rectally into the colon of rabbits at a dose of 2 ml/kg. CHE reached a plateau after 20 min at 109 nmol/min/kg. Using hypoxemia as a cause for bowel ischemia, at PAO2 = 38 torr, we noted a marked decreased in CHe from 110 nmol/min/kg to 75 nmol/min/kg (p less than 0.025). Because helium absorption from the colon is diffusion limited, a model can be developed relating "subvillus" colonic blood flow to pulmonary helium clearance. From this model we would predict the hypoxemia induced change in CHe to be secondary to colonic hypoperfusion. This type of indirect monitoring could be useful in detecting patients with bowel ischemia.

Animals↗
PubMed2005

A case of primary syphilis in the rectum.

A 30-yr-old man was referred for suspicious rectal cancer because of ulcerated lesions in the rectum and a palpable mass in left inguinal area. Sigmoidoscopy showed two indurated masses and histologic evaluation of biopsy revealed obliterative endarteritis with heavy plasma cell infiltration. Both venereal disease research laboratories (VDRL) and fluorescent treponemal antibody absorption (FTA-ABS) tests were positive. After injection of penicillin G benzathine for 3 weeks, the rectal chancre and the palpable mass disappeared.

Adult↗
PubMed2002

Bioavailability and in vitro oesophageal sticking tendency of hydroxypropyl methylcellulose capsule formulations and corresponding gelatine capsule formulations.

The overall aim of the present study was to widen our knowledge about the biopharmaceutical behaviour of novel hydroxypropyl methylcellulose (HPMC)-based two-piece capsules by comparing them with the classic hard gelatine capsules. Firstly, the tendency of the HPMC capsules to stick to isolated porcine oesophageal preparation was evaluated. The force needed to detach the HPMC capsules from the oesophagus was significantly lower than that for the gelatine capsules (P<0.001), which is evidently an advantage of this new dosage form. The second aim was to investigate the possibility of preparing sustained-release capsules using different powdered HPMCs as diluents (K100, K4M and K15M) and the effect of the molecular weight of HPMC powder on the in vitro and in vivo behaviour of the capsules. In addition to peroral drug administration also rectal dosing was applied. Two groups of eight healthy volunteers participated in randomised, cross-over, single-dose studies. One group was administered capsules orally and the other rectally. There were no marked differences in the bioavailability properties of either the oral or rectal HPMC capsules containing ibuprofen as model drug as compared with corresponding gelatine capsule formulations. Using different viscosity grades of HPMC powders as diluents it was possible to control the absorption rate of the model drug both from gelatine and HPMC capsules as far as the oral route was concerned. After rectal administration there were no statistically significant differences between the formulations containing different grades of HPMC powder. Only partial correlation was observed between the results of the bioavailability studies and the in vitro dissolution studies. From a biopharmaceutical point of view these two shell materials can be regarded as interchangeable.

Administration, Oral↗
PubMed1986

The effect of activated charcoal on the bioavailability of piroxicam in man.

The effect of single and multiple oral doses of activated charcoal (a.c.) on the plasma concentrations of piroxicam was investigated in a cross-over study in 6 healthy volunteers after oral and rectal doses of 20 mg piroxicam. 50 g a.c. swallowed 5 min after the oral administration of one capsule of piroxicam almost completely prevented the absorption of the drug. 70 g a.c. per day were given in multiple doses over the interval of 10-58 h after the oral and 2-58 h after the rectal administration of piroxicam. This treatment reduced the mean bioavailability of piroxicam by 41.7% (oral) or 48.8% (rectal), relative to the control. The apparent total clearance increased significantly (p less than 0.05) to 163.6% (oral) or 187.9% (rectal) of the control. Half-lives of elimination were reduced on the average from 40.2 h to 19.6 h after the oral dose and from 40.7 h to 21.6 hours after the rectal dose under the a.c. treatment. It is inferred from these results that piroxicam is subject to enteral circulation. A.c. appears useful as an antidote in acute intoxications from piroxicam.

Adult↗
PubMed1981

Mechanism of chemotherapeutic drug action in mouse vaginal epithelium.

The mouse vaginal assay was modified to study mechanisms of drug action in epithelial cells in relation to the cell cycle. An evaluation of the labeling index, mitotic index, and the percent labeled mitoses in the vaginal epithelium was used to determine the site of drug action in the cell cycle. Systemic absorption from the vaginal epithelium was also monitored by these same measurements in rectal mucosa. Thirty drugs was tested; 17 showed cell kinetic perturbations in the vaginal mucosa and four of these had both vaginal (local) and rectal (systemic) effects. Thirteen drugs had no effect, suggesting inadequate concentration, penetration, duration of drugs exposure, or lack of biochemical action. These 30 drugs were tested in concentrations and vehicles also used for topical screening in psoriatic patients. Only 15 of the 30 drugs tested in this model predicted the clinical results.

Animals↗
PubMed1985

Improvement of bioavailability of poorly absorbed drugs. II. Effect of medium chain glyceride base on the intestinal absorption of cefmetazole sodium in rats and dogs.

The effect of medium chain glyceride (MCG) on the intestinal absorption of cefmetazole sodium (CMZ) was investigated in rats and dogs. In rats, MCG containing glyceryl mono-, di- and tri-caprylate enhanced the intestinal absorption of CMZ after intraduodenal administration, though the promoting effect of MCG was less than that after rectal administration. The promoting effect of MCG was found to be mainly due to glycerylmonocaprylate and dependent on the dosage of MCG. The plasma CMZ levels after intraduodenal administration as MCG solution tended to be slightly higher than those observed after administration as MCG emulsion, though the differences were found to be statistically insignificant. Moreover, the intestinal absorption of CMZ after intraduodenal administration as MCG emulsion was decreased significantly by increasing the amount of water in the emulsion. The promoting effect of MCG in dogs was more clearly demonstrated in the lower intestine than in the upper intestine. Furthermore, the oral bioavailability of pharmaceutical formulations of CMZ was also investigated in dogs. When enteric coated capsules filled with MCG solution were administered to dogs, the bioavailability of CMZ was enhanced significantly.

Animals↗