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PubMed1995

Pharmaceutical evaluation of carbamazepine suppositories in rats.

The absorption of carbamazepine (CBZ) after rectal administration in the form of a suppository was studied in rats. CBZ suppositories were prepared with Witepsol H-15 (H-15), Witepsol S-55 (S-55) or polyethylene glycol 6000 (PEG) bases by moulding procedure. An in vitro investigation was undertaken using a dissolution apparatus. The in vitro dissolution rate of CBZ showed marked differences among the bases in the order PEG > H-15 > S-55. An in vivo study demonstrated marked differences in the time required to reach peak plasma concentration (Tmax) of CBZ after rectal and oral administration: the absorption of CBZ from PEG base was the most prolonged among these bases (in the order PEG > H-15 > S-55 > ORAL). Comparison of the area under the plasma concentration-time curve (AUC) of CBZ after rectal administration of the three different suppositories with those after intravenous and oral administration showed no significant differences in the AUC among the five preparations. These results suggest the possibility that CBZ suppositories can replace oral treatment for epilepsy.

Animals↗
PubMed1995

Absorption enhancement of a hydrophilic model compound by verapamil after rectal administration to rats.

The use of verapamil as an absorption enhancer for the paracellular route in-vivo was studied using FITC-labelled dextran (molecular weight 4000) (FD-4) as a hydrophilic model compound for transport enhancement. The kinetics of FD-4 after intravenous doses of 1 or 10 mg could be described by a two-compartment model with a systemic clearance of approximately 2 mL min-1 and a terminal plasma half-life of approximately 36 min. Rectal administration to rats, performed as a rectal infusion of 10 mg FD-4 together with 7 mM verapamil, resulted in a 10-fold increase in the percentage of the dose absorbed over a 5-h period compared with the control and a 6-fold increase compared with a bolus administration, although the total amount absorbed remained relatively low (approx. 3% maximum). Large inter-animal variation in effect values were noted. The data indicate that although verapamil is able to enhance the absorption of hydrophilic compounds in-vivo, practical application of verapamil for this purpose doses not seem feasible.

Administration, Rectal↗
PubMed1975

Plasma concentrations of diazepam and its metabolites after peroral, intramuscular, and rectal administration. Correlation between plasma concentration and sedatory effect of diazepam.

Plasma levels of diazepam, N-demethyldiazepam and free oxazepam were measured gaschromatographically in ten healthy volunteers after 5 mg of diazepam perorally, intramuscularly and rectally (with three different kinds of suppositories). The best absorption of diazepam was found after peroral administration. After an intramuscular injection a delayed absorption with low plasma concentrations of diazepam was found. The basal component of a diazepam suppository seems to have a great effect on the rectal absorption of diazepam. Two of the three different kinds of diazepam suppositories caused higher plasma diazepam concentrations than the intramuscular injection of the drug. There were no great differences in the amount of the metabolites of diazepam after different kinds of administration. The subjective sedatory effect of diazepam lasted approximately as long as the fast distribution of diazepam from plasma took place. A very highly significant correlation between plasma concentration and subjective sedatory effect of diazepam after a single dose was found.

Administration, Oral↗
PubMed2000

Pharmacokinetics of three formulations of ondansetron hydrochloride in healthy volunteers: 24-mg oral tablet, rectal suppository, and i.v. infusion.

The absolute bioavailability and pharmacokinetics of three formulations of ondansetron hydrochloride 24 mg--an oral tablet, an intravenous solution, and an extemporaneous rectal suppository--were studied. Twelve healthy, nonsmoking volunteers (six men and six women) were given ondansetron in a study with a three-way cross-over design. All subjects received each dosage form on the same day in the following order: oral tablet, rectal suppository, and intravenous infusion. Administrations were separated by one week. Blood sampling times varied, depending on the administration route. Mean absolute bioavailability for the oral tablet and the rectal suppository differed significantly. Absorption of ondansetron was prolonged when it was administered as the rectal suppository. Absolute bioavailability for the 24-mg tablet was similar to that for other tablet strengths in previous studies. All subjects completed the study without significant adverse effects. Absorption of ondansetron from the rectal suppository was prolonged compared with the oral tablet and the i.v. infusion. Bioavailability for the 24-mg suppository formulation was considerably lower than for the 24-mg tablet.

Antiemetics↗
PubMed1984

Effects of migraine attack and metoclopramide on the absorption of tolfenamic acid.

The effect of acute migraine attack and rectally given metoclopramide on the absorption of orally given tolfenamic acid (300 mg) was investigated in seven female patients in a crossover study consisting of four phases, two without migraine and two during migraine. Metoclopramide hydrochloride (20 mg) or placebo was given double-blind. Migraine attacks delayed the absorption of tolfenamic acid. Serum concentrations of tolfenamic acid 1.5 and 2 h after drug administration remained smaller, the peak serum concentration (tmax) occurred later and the area under the serum concentration-time curve between zero and 2 h (AUC0-2 h) remained decreased during migraine. Metoclopramide pretreatment in migraine attacks increased the serum concentration of tolfenamic acid at 1.5 h, but its peak concentration, time to peak concentration and the AUC0-5 h remained unchanged as compared with the values obtained with tolfenamic acid alone. Between the absorption of tolfenamic acid without migraine and after metoclopramide pretreatment during migraine no significant differences existed. When the patients were studied without migraine the serum concentrations of tolfenamic acid 45 min and 60 min after its administration were higher after metoclopramide than after placebo pretreatment. During migraine attacks the serum concentrations and the AUC0-5.5 h of metoclopramide were slightly lowered. The impairment of drug absorption by migraine was not related to the duration or severity of the attack. The observed changes in drug absorption during migraine attacks are obviously due to the delay in gastric emptying. Rectally administered metoclopramide accelerates the absorption of orally given tolfenamic acid.

Absorption↗
PubMed1981

Serum theophylline levels after use of an anhydrous crystalline theophylline suppository.

The absorption of theophylline from a suppository not containing ethylenediamine was tested in 9 healthy volunteers. AUC after rectal administration of anhydrous crystalline theophylline 250 mg (AUCrectal) was compared with the AUC after oral administration of microcrystalline theophylline 250 mg (Nuelin; AUCoral) in a randomized, cross-over study. The ratio AUCrectal/AUCoral was 0.75 at 10h, and the ratio AUCrectal x beta rectal/AUCoral x beta oral extrapolated to infinite time was 0.83. A mean concentration of 5.7 micrograms/ml was reached 3.7 h after a single rectal dose. The absorption studied were performed with suppositories stored for 15 weeks at 22 degrees C. No effect on the in vitro release rate of theophylline from the suppository was observed during storage at room temperature from 3 to 31 weeks after production. Since aminophylline suppositories are known to decompose upon storage, the results suggest that a formulation without ethylenediamine is preferable for the rectal administration of theophylline.

Administration, Oral↗
PubMed1999

Correlation of in vitro and in vivo paracetamol availability from layered excipient suppositories.

An in vivo investigation of paracetamol availability was carried out on eight healthy volunteers, comparing two paracetamol suppository formulations prepared using two different gliceride bases, a fast drug-releasing one and a slow drug-releasing one, i.e. Witepsol H15 and W35, respectively. The formulations were selected on the basis of a previous in vitro drug release study, which showed that, by superimposing the excipients in two layers within the same suppository, the drug release kinetics could be modulated using different ratios between the two layers. The comparison between the two different formulations in terms of plasma profiles and total amounts of drug excreted in urine revealed an increase in the extent of drug absorption from the layered excipient suppository. As the W35 has a higher monoglyceride content than the H15, this improved paracetamol availability could be ascribed to the absorption-enhancing effect of the monoglycerides. Moreover, the W35 has also a higher viscosity, which could possibly cause the suppository to be retained for a longer time in the lower part of the rectum, where the blood is drained directly to the systemic circulation. It was therefore hypothesized that the enhanced paracetamol availability could be also due to a liver bypass mechanism. For a further examination of the paracetamol absorption kinetics after rectal administration, a one-compartment model was fitted to the drug plasma concentration data. This approach allowed to draw absorption versus time profiles, which showed that a retardation actually occurred in paracetamol absorption when using suppositories containing the slow drug releasing excipient W35. These absorption data were then employed for an A level in vitro-in vivo correlation testing, and a linear relationship was found between in vitro release rate and in vivo absorption rate, both for fast releasing and for the layered excipient suppositories.

Acetaminophen↗
PubMed1988

[The effect of exogenous factors on prececal nutrient and amino acid absorption, ascertained from swine with ileo-rectal anastomoses. 3. The effect of crude fiber-rich coarse meal supplements to a basic ration].

In digestion trials using pigs fitted with ileo-rectal anastomoses and parallel intact pigs the influence of wheat straw meal (WSM) or grass meal (GM) supplemented on two different levels to a basal diet was examined with regard to nutrient and amino acid digestibility resp. absorption. Both roughages reduced, obviously because of their high cell wall contents, nearly at equal amounts and partly significantly the precaecal as well as the total digestibility of dry matter, organic matter, carbohydrates (= crude fibre + NFE), crude fibre and hemicelluloses (arabinose, xylose). By the roughage supplementations the crude protein digestibility at the terminal ileum was less reduced than at the end of the total digestive tract, the starch digestibility was hardly influenced and that of ether extract mostly increased. In comparison with precaecal glucose and fructose digestibilities it could be shown that the anthrone method is not suitable for determinations of the precaecal digestibility of water soluble carbohydrates. Beside these compounds other substances in the ileum digesta must evidently be dyed by anthrone too. The crude protein digestibility and the amino acid absorption were precaecally hardly or not reduced by WSM supplementations, therefore it can be concluded that it is possible to dilute the energy concentration in diets (e.g. for sows) by addition of WSM without impairing protein digestion and amino acid absorption. The GM supplementations, however, impaired protein digestibility and amino acid absorption of the whole diet, probably caused by the encrusted, possibly heat damaged protein present in the GM itself. When the roughage supplemented diets were fed, the excretion of nitrogen compounds in the faeces was enlarged due to the more intensive bacterial activity in the hind gut and the additional sorption effects to cell wall substances, so that a too low apparent and also true digestibility is made believe. The applicability of the difference method to the calculation of protein and amino acid digestibilities in roughages is very questionable because of their low contents and the missing additivity. The crude fibre and hemicellulose digestibility values calculated by the difference method demonstrate for the both roughages--in spite of high standard deviations--that the precaecal digestibility of crude fibre is about zero and that of the hard lignified hemicellulose fraction in contrast to the predominantly endospermic hemicelluloses of the basal diet is very low. The faecal crude fibre and hemicellulose digestibilities of WSM--especially on the lower supplementation levels--are markedly worse than those of GM.

Amino Acids↗
PubMed2000

Enhanced enteral bioavailability of vancomycin using water-in-oil-in-water multiple emulsion incorporating highly purified unsaturated fatty acid.

The aim of this study was to evaluate the potential of an emulsion incorporating unsaturated fatty acids to improve the mucosal absorption of poorly absorbed drugs from rat intestinal loops in situ, using a water-in-oil-in-water (W/O/W) multiple emulsion. Vancomycin hydrochloride (VCM) was used as a model drug with low oral bioavailability. The entrapment efficiency of VCM in the emulsion was approximately 60% and remained constant over storage for 1 month at 4 degrees C. The emulsion incorporating C18 unsaturated fatty acids or docosahexaenoic acid (DHA) markedly enhanced VCM absorption after colonic and rectal dosing. The effectiveness of DHA on VCM colonic absorption improvement was the same as that of oleic acid, and less than that of linoleic and linolenic acids. For rectal dosing, bioavailability was similar among various emulsions, in the range 40-50%. The effect of the emulsion incorporating oleic acid or DHA on improving VCM enteral bioavailability was not increased proportional to the incorporated amount. The electrical resistance of membranes was not changed by the incorporation of various fatty acids in emulsions. Our results indicated that W/O/W emulsions incorporating C18 unsaturated fatty acid or DHA were useful carriers for improving the absorption of poorly absorbable drugs via the intestinal tract without gross changes to tight junction function.

Administration, Rectal↗
PubMed1991

[Experimental study of per-rectal portal scintigraphy using 99mTc-EHIDA].

We discovered that 99mTc-EHIDA commonly used for hepatobiliary scintigraphy could also be administered per-rectally, with adequate absorption and optimal visualization of the portal system. To evaluation its usefulness, we experimented on rabbits using the method. Portal scintigraphy with rectal administration of 99mTc-EHIDA, 123I-IMP and 99mTc-RBC were performed in normal rabbits and in extrahepatic portal shunt model rabbits. Images of the liver and thorax were obtained and shunt indices were calculated from the count values of liver and lung or heart. Then the shunt indices were compared with shunt rate derived from direct injection of 99mTc-MAA into inferior mesenteric vein. Correlation between shunt rate of 99mTc-MAA and shunt indices of 99mTc-RBC, 123I-IMP and 99mTc-EHIDA were 0.64, 0.75 and 0.78, respectively, with 99mTc-EHIDA having the most favourable results. We concluded that 99mTc-EHIDA per-rectal portal scintigraphy is a noninvasive, quantitative, inexpensive and simple method for evaluation of portal circulation system. Also, we think that this method would be applicable to human usage from our experience with normal volunteers.

Administration, Rectal↗
PubMed1983

Serum concentration of clonazepam after rectal administration.

The purpose of the present study was to evaluate the absorption of clonazepam administered rectally. 10 adult non-epileptics were given 0.02 mg clonazepam/kg body weight, and blood samples were drawn 0, 2, 5, 7, 10, 15, 30 and 60 min after administration. The concentrations were measured by gas-chromatography. To gain an impression of the serum concentration after intravenous administration, 2 persons were given 1 mg clonazepam and blood samples were drawn and analyzed in the same way as after rectal administration. Peak values occurred 10 to 30 min after rectal administration; the values were between 18 and 57 nmol/l. After intravenous administration, the values were very high within the first 10-15 min; hereafter the concentrations were about the same level as the peak values after rectal administration, indicating that clonazepam is well-absorbed after rectal administration and can be used in the treatment of status epilepticus, possibly in larger doses than those used in this study.

Adult↗
PubMed1997

Rectal administration of N-acetylcysteine in swine: a pilot study.

The purpose of this pilot study was to determine if N-acetylcysteine (NAC) administered via the rectal route in swine is absorbed into the systemic circulation. Fasting swine were anesthetized, intubated, monitored and i.v. access was obtained by femoral cutdown. NAC was administered into the rectal vault (2.0 g/kg) via a balloon-tipped Foley catheter inserted into the animals' rectum. NAC administered via the rectal route resulted in systemic absorption as determined by spectrophotometric methods in 5 of the 7 study animals. This study provides important information regarding the development of a potential alternative route for the administration of NAC.

Absorption↗
PubMed2006

Evaluation of mucin as a release enhancer for rectal delivery of glibenclamide.

In this work mucin was evaluated as a release and absorption enhancer for glibenclamide from rectal glycerogelatin suppository. Glycerogelatin suppositories containing different ratios of glibenclamide to I-mucin (insoluble), S-mucin (soluble) and sodium salicylate respectively, were formulated using the fusion method. The suppositories were evaluated using standard parameters. Release studies were carried out in phosphate buffer (pH 7.6). The pharmacodynamic (PD) evaluation of the formulations was carried out on normoglycaemic albino rats. The results of the physical tests showed that the suppositories possessed high resistance to rupture and had uniformity of weight and drug contents. The erosion times of the suppositories with I-mucin, S-mucin and sodium salicylate were shorter than glycerogelatin suppositories BP without any release enhancer (control). Analysis of the release data showed that the release pattern was bi-phasic with initial fast release and subsequent slow release of the glibenclamide from the suppositories. The release mechanism followed first order kinetics. All the suppositories containing either S-mucin, I-mucin or sodium salicylate showed better glibenclamide release than the control without any release enhancer (p < 0.05). The pharmacodynamic studies showed that the overall glucose lowering effect in rats was greater in S-mucin suppositories than in sodium salicylate and I-mucin suppositories. The results of this study indicated that mucin extracted from Bovine spp. could be used to enhance the release and subsequent absorption of glibenclamide from rectal glycerolgelatin suppositories.

Adjuvants, Pharmaceutic↗
PubMed1994

Circulation of estrogens introduced into the rectum or duodenum in pigs.

To determine the absorption and metabolism of 17 beta-estradiol (E2) by the rectum of the pig, 10 mg of crystalline E2 was placed in the rectum of prepubertal gilts in Experiment 1. Blood samples were subsequently obtained from hepatic portal and jugular veins and plasma was assayed for E2, estrone (E1), 17 beta-estradiol-glucuronide (E2G), estrone-glucuronide (E1G) and estrone-sulfate (E1S). Concentrations of E2, E1, E2G, E1G, and E1S rose in the hepatic portal vein within 30 min and remained elevated for several hr. Concentrations of E2 in the hepatic portal vein represented 3% of the total estrogen detected in the hepatic portal vein during the 5 hr sampling period, indicating that most of the E2 was metabolized prior to entering the hepatic portal vein after absorption by the rectal mucosa. Concentrations of E2, E1, E2G, E1G, and E1S rose in the jugular vein and remained elevated for several hr. The rise in E2 and E1 in the jugular vein may have come from E2 and E1 in venous circulation from the rectum that entered the inferior vena cava bypassing the hepatic portal vein and liver. The net result of absorption of E2 from the rectum of gilts was a large rise in unconjugated and conjugated E2 and E1 in the peripheral circulation. In Experiment 2 prepubertal gilts fitted with jugular, hepatic portal, duodenal, and gall bladder catheters were infused into the duodenum with bile from pregnant gilts. Concentrations of E2, E1, E2G, and E1G were determined in gallbladder bile of gilts before infusion and at 470 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Rectal↗
PubMed1993

[The pharmacokinetic characteristics of theophylline in patients with chronic nonspecific intestinal diseases in relation to its routes of administration into the gastrointestinal tract].

Theophylline pharmacokinetics was investigated upon introduction of euphylline (0.15 g) at four levels of gastrointestinal tract: orally (20 patients), into the jejunum (15 patients) at enterogastroduodenoscopy, in the ileocecal area (8 patients) at colonoscopy and rectally (9 patients). Absorption speed depended on the variant of the gastrointestinal introduction rather than on the variant of chronic nonspecific intestinal disease, and appeared maximal in the drug introduction into the jejunum. Concentration and area under curve became maximal in minor participation of the liver in primary capture and biotransformation of theophylline. Reduced theophylline doses are recommended in lower hepatic metabolism of the drug, in hepatic hypofunction, in rectal route of administration.

Administration, Rectal↗