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PubMed1981

Diazepam in rectal solution as premedication in children, with special reference to serum concentrations.

The absorption of rectal diazepam solution was studied in 22 children aged 1-9 yr by measuring serum concentrations. The mean dose was 0.27 +/- 0.09 mgkg-1. The mean serum concentration was 98.5 +/- 53.5 ng ml-1 4 min after administration and 206.7 +/- 105.8 ng ml-1 at 11 min. The correlation between dose and serum concentration was statistically significant at both times. With a dose of 0.4-05 mgkg-1 an adequate serum concentration was achieved within 5-6 min. No side-effects were observed. A rectal solution provides a faster, more effective and reliable alternative to tablets and suppositories, and to the uncertain i.m. injection of diazepam. Meticulous nursing is important.

Child↗
PubMed1981

Prostaglandin synthesis inhibitors in ulcerative colitis: flurbiprofen compared with conventional treatment.

It has been suggested that prostaglandins (PGs) play a pathogenetic role in ulcerative colitis (UC) and that treatment with inhibitors of PG synthesis might be of therapeutic benefit. We therefore performed a one-week open trial to compare the effects of oral flurbiprofen with those of conventional therapy with corticosteroids and sulphasalazine, in two groups of patients with active UC. Mean rectal mucosal release of PGE2, measured by in vivo rectal dialysis, fell by 44% (P less than 0.05) after one week's conventional treatment, and the effect of flurbiprofen was not significantly different. However, the patients given flurbiprofen fared significantly worse than those given conventional therapy in respect of rectal mucosal appearance at sigmoidoscopy (P = 0.01), rectal electrical potential difference (p less than 0.01), rectal mucosal sodium absorption (P = 0.01) and rectal bleeding (P less than 0.05). Furthermore, flurbiprofen-treated patients showed significant deteriorations in rectal potential difference (P less than 0.05) and sodium absorption (P less than 0.05). These results do not support the hypothesis that increased mucosal PG production is of major pathogenetic importance in active UC, and suggest that flurbiprofen is unlikely to prove a useful alternative to conventional therapy.

Colitis, Ulcerative↗
PubMed1981

Bioavailability of rectally administered valproic acid syrup.

The bioavailability of commercially available valproic acid (VPA) syrup was studied following rectal administration in both dogs and children. Six dogs were studied following both oral (PO) and rectal (PR) administration of a dilute VPA syrup given in a dose of 40 mg per kilogram. There was no significant difference (p greater than 0.1) in the area under the serum concentration-time curve (AUC) between the oral (201.1 mg L-1hr) and rectal 219.6mg L-1hr) routes of administration. Four children were given VPA syrup by the rectal route. In three patients on maintenance VPA therapy, absorption following rectal administration was similar to that following oral administration. In a fourth child, VPA serum levels following an initial rectal dose of 20 mg per kilogram reached a maximum of 42 mg per liter 2 hours after the drug was given. These results indicate that the bioavailability of a diluted VPA syrup given rectally is comparable to that following oral administration. Rectal administration of VPA syrup appears to be a satisfactory alternative when the oral route is unavailable.

Animals↗
PubMed1981

Some pharmacokinetic properties and bioavailability by oral and rectal route of piroxicam in rodents and in man.

In a comparative study on rodents and on man the fundamental pharmacokinetic properties of 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (piroxicam) were assessed and the bioavailability of the drug after oral and rectal administration was determined. It was found that: the plasma half-life is much longer in man (ca. 35 h) than in rodents (3--5.5 h in the rabbit, 5 h in the rat and mouse). The long plasma disappearance time in man is attributed to the relatively strong binding with the plasma proteins. A thorough pharmacokinetic analysis in the rabbit revealed a two-compartment distribution of the drug with an intercompartmental t 1/2 0.67 h and an excretion + metabolisation t 1/2 of 3.16 h. The extremely low excretion of the drug as such or as the glucuronide in the bile and urine suggests that the main excretion route is metabolic. The rectal bioavailability is similar to the oral bioavailability both in rabbit and rat and in man. Comparison of the AUC after i.v. injection with the AUCs after oral and rectal administration in the rabbit seems to show that absorption by rectal and oral route is quantitative.

Administration, Oral↗
PubMed1997

Mechanism of absorption enhancement in humans after rectal administration of ampicillin in suppositories containing sodium caprate.

PURPOSE: The medium chain fatty acid sodium caprate (C10) is approved as an absorption enhancer but its mechanism of action has not been studied in humans. The aim of this study was to investigate the mechanism of action of C10 in human subjects after rectal administration. METHODS: Twelve healthy human subjects were randomised to receive ampicillin suppositories with (AM-C10) or without (AM) C10. Serum and urine samples were collected and analysed for ampicillin by HPLC. Rectal biopsies were taken before and 25 min (approximate time of maximum serum concentration, Cmax, for ampicillin) and 185 min (during the final part of the elimination phase) after rectal administration of the suppositories. The osmolality of the rectal fluid was also measured. RESULTS: AM-C10 administration increased Cmax, area under the serum concentration-time curve (AUC) and urinary recovery of ampicillin 2.6-, 2.3- and 1.8-fold, respectively, compared to AM. Histological examination of the biopsies showed that AM-C10 exposure resulted in reversible mucosal damage that occurred at the same time as the Cmax for ampicillin while AM prolonged mucosal damage. A reversible increase in rectal fluid osmolality was observed with both treatments. CONCLUSIONS: AM-C10-enhanced absorption of ampicillin coincides with non-specific damage to the rectal mucosa. C10 itself as well as the suppository base and the hyperosmolality of the rectal fluid contributed to this effect. However, the histological damage was reversible with AM-C10, suggesting that C10 also has a protective effect on the rectal mucosa.

Adult↗
PubMed1984

Rectal administration of morphine hydrogel: absorption and bioavailability in women.

Seven patients undergoing radiological treatment for carcinoma of the uterus were given morphine intramuscularly (0.15 mg X kg-1) and morphine in a starch hydrogel rectally (0.56 mg X kg-1) on two separate occasions. The hydrogel preparation was used to order to improve the contact between the rectal mucosa and thus improve and possibly prolong the absorption of morphine. Plasma concentrations of morphine were followed for 8 h and analysed with a GC/MS technique. It was found that 45-120 min after administration of morphine hydrogel, a mean maximum plasma morphine concentration of 61 ng X ml-1 was obtained. After 8 h, the mean plasma concentration was 10 ng X ml-1. The mean biological availability of morphine hydrogel was 48% (range 31-72%). It is suggested that morphine hydrogel, given rectally, can be clinically useful.

Absorption↗
PubMed1991

Effect of ibuprofen in patients with severe sepsis: a randomized, double-blind, multicenter study. The Ibuprofen Study Group.

OBJECTIVE: To evaluate the safety and physiologic actions of ibuprofen in patients with severe sepsis. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Three university hospital medical ICUs. PATIENTS: Twenty-nine patients with clinical evidence of sepsis and the need for hemodynamic monitoring with a pulmonary artery flotation catheter. INTERVENTIONS: Thirteen patients received placebo and 16 received ibuprofen that consisted of 600 mg (n = 11) or 800 mg (n = 5) iv over 20 mins, followed by three 800-mg doses administered as a rectal solution every 6 hrs. The initial iv dose was given within 4 hrs of the presumptive diagnosis of sepsis. MEASUREMENTS AND MAIN RESULTS: The peak circulating total ibuprofen concentration after the iv dose (49.4 +/- 4.5 micrograms/mL, mean +/- SEM) was higher than peak concentrations after the three rectal doses (17.0 +/- 2.7, 16.4 +/- 3.0, 16.0 +/- 3.1 micrograms/mL). Both routes of ibuprofen administration were well tolerated. Frequent monitoring for gastrointestinal bleeding and assessment of renal and hepatic function failed to demonstrate significant differences between ibuprofen and placebo. Because a trend for reduced creatinine clearance was observed at 8 hrs in the ibuprofen group, nephrotoxicity of this drug in sepsis cannot be excluded. Temperature decreased significantly within 4 hrs of the initial dose of investigational therapy in patients who received ibuprofen (38.5 +/- 0.3 degrees to 37.0 +/- 0.2 degrees C, p less than .001). However, despite this significant change in temperature, we were unable to detect significant differences in hemodynamic and respiratory values or survival when ibuprofen-treated patients were compared with controls. CONCLUSIONS: Ibuprofen was well tolerated when administered iv and rectally to patients with severe sepsis, although drug absorption was poor with the rectal route. Significant antipyretic effects of ibuprofen were demonstrated. Although an excellent safety profile characterized ibuprofen in this study, the absence of ibuprofen-associated toxicity may have been secondary to poor rectal absorption of the drug. Our results support the continued clinical investigation of ibuprofen in sepsis, using an all-intravenous route of administration.

Administration, Rectal↗
PubMed1984

Colonic absorption of acetylsalicylic acid in the rat.

Aspirin is absorbed in the colon by passive diffusion to a significant degree in spite of the alkaline pH of the colonic lumen. Aspirin absorption by the colon is enhanced by increasing the hydrogen ion concentration. Butyric acid, by markedly reducing the absorption rate of aspirin, may be partially responsible for the unpredictable absorption of rectally administered aspirin. The addition of glycerol to aspirin preparations does not hinder the absorption of aspirin by the colon.

Animals↗
PubMed1995

Absorption of diazepam after its rectal administration in dogs.

A cross-over study was performed in 6 healthy mixed-breed dogs and 4 healthy Beagles. Diazepam was administered per rectum to Beagles (0.5 mg/kg of body weight) and mixed-breed dogs (2 mg/kg), and IV (0.5 mg/kg) to both groups of dogs. Each dog received the drug by both routes, with a 1-week washout period between dosages. After diazepam administration, blood samples were collected to measure plasma concentration of diazepam and its active metabolites, desmethyldiazepam and oxazepam, by use of reverse-phase high-performance liquid chromatography (HPLC). Systemic availability was assessed by comparing the area under the curve for diazepam metabolites for each route of administration. Mean (+/- SD) diazepam concentrations in plasma after rectal administration were low in comparison with those obtained after IV administration, with systemic availability of only 7.4 (+/- 5.9) and 2.7 (+/- 3.2)% for the high and low dose, respectively. However, diazepam was converted to its metabolites within minutes after administration. Accounting for the total concentration of benzodiazepines (diazepam plus desmethyldiazepam and oxazepam) in plasma, systemic availability was 79.9 (+/- 20.7) and 66.0 (+/- 23.8)% for the high and low dosage, respectively. After IV administration, diazepam concentration decreased, with a half-life of only 14 to 16 minutes, but desmethyldiazepam and oxazepam concentrations decreased more slowly, with a half-life of 2.2 to 2.8 hours and 3.5 to 5.1 hours, respectively. Each of the metabolites is reported to have anticonvulsant activity. After rectal administration of the high dose, mean total benzodiazepine concentration was above 1.0 microgram/ml within 10 minutes and was maintained above this concentration for at least 6 hours. We conclude that diazepam is absorbed after rectal administration in dogs, and that the pharmacologic effects are probably caused by the active metabolites, not the parent drug. Samples also were analyzed by use of a nonspecific commercial benzodiazepine fluorescence polarization immunoassay (FPIA). Correlation between the FPIA and HPLC assay was strongest for diazepam (R2 = 0.84), weak for desmethyldiazepam (R2 = 0.09), and nonexistent for oxazepam. We conclude from a comparison of assays that HPLC is preferred over the FPIA method for measuring benzodiazepines in dogs.

Absorption↗
PubMed1996

Effect of some amino acids on the rectal irritation caused by sodium caprate in conscious rats.

The effects of some amino acids such as L-glutamine (Gln), L-arginine (Arg) and L-methionine (Met) on rectal irritation caused by sodium caprate were studied in rats. Rectal irritation was assessed by the balloon method in fasting conscious rats. This method is based on measuring rectal contractions due to possible irritation caused by the presence of drugs and/or adjuvants in the rectum. Strong contractions were observed after rectal administration of an aqueous solution of 100 mM sodium caprate. However, the presence of Gln, Arg or Met (100 mM) in sodium caprate (100 mM) solution resulted in a significant decrease in the intensity of the rectal contraction caused by sodium caprate. The rectal absorption-promoting effect of sodium caprate on 6-carboxyfluorescein (6-CF) was examined following administration with amino acids in rats. The absorption of 6-CF was not influenced by the concurrent administration of amino acids. In addition, the rectal tissue interaction of sodium caprate, with or without Gln, was examined. The concentration of sodium caprate in rectal tissue was reduced by the presence of Gln.

Amino Acids↗
PubMed1993

[Comparison of bioavailability of salbutamol between oral and rectal administration in rabbits].

In order to obtain a basic knowledge for developing the rectal dosage form of salbutamol (SB), a comparison of the bioavailability was made between oral and rectal administrations. After the intravenous, oral and rectal dosing of SB solution in rabbits, SB and its glucuronide (SBG) in plasma and urine were determined. The bioavailability estimated by the area under the blood concentration-time curve (AUC) of SB from 0 to 9 h after oral and rectal administrations were 1.1 +/- 0.5% and 7.8 +/- 2.2% (mean +/- S. E., n = 5), respectively. Percent of dose excreted in urine as total SB (SB+SBG) 10 h after oral and rectal administrations were 77.3 +/- 3.82% and 9.80 +/- 0.15% (mean +/- S. E., n = 3), respectively, which indicating relatively good oral and poor rectal SB absorption. A partial avoidance of first-pass-effects might contribute to higher bioavailability after the rectal administration.

Administration, Oral↗
PubMed1986

Effect of glucocorticoids on rectal transport in normal subjects and patients with ulcerative colitis.

The acute effects of single pharmacological doses of glucocorticoid hormones on net electrolyte and water transport and electrical potential difference (pd) in the rectum was studied in control subjects and in patients with either active or inactive ulcerative colitis, using a dialysis technique. Compared with 17 control subjects, nine patients with active ulcerative colitis exhibited marked decreases in net sodium absorption and rectal pd, while these transport parameters were normal in six patients with inactive ulcerative colitis. Intravenous administration of hydrocortisone hemisuccinate (100 mg) resulted five hours later in significant and quantitatively similar increases in net sodium and water absorption and pd in nine control subjects, seven patients with active ulcerative colitis, and six patients with inactive ulcerative colitis. Intravenous administration of methylprednisolone phosphate (40 mg) to eight control subjects produced increases in net sodium and water absorption and pd five hours later, which did not differ significantly from those produced by hydrocortisone; methylprednisolone induced similar changes in two patients with active ulcerative colitis. These results indicate that single pharmacological doses of glucocorticoids stimulate acute increases in rectal sodium and water absorption in control subjects and in patients with acute ulcerative colitis. The ability of systemically administered glucocorticoids to reduce diarrhoea in ulcerative colitis may therefore be related to direct effects on distal colonic sodium and water transport, as well as to their better known anti-inflammatory action.

Acute Disease↗
PubMed1977

Studies on the absorption and disposition of meptazinol following rectal administration.

1 Rectal administration of the new analgesic drug, meptazinol, resulted in rapid absorption of the compound both in the monkey and in man. Peak plasma levels were observed within 0.5 h of dosing. 2 Absorption of the drug following rectal administration was extensive as shown by the recovery of 65-90% of the dose in the urine. 3 Despite substantial inter-individual variation in the observed maximum plasma concentrations of the drug, it was still evident that concentrations after rectal dosage were considerably higher than when the same dosage was given orally. 4 Elimination of the drug from plasma took place rapidly in an apparently mono-exponential manner in both species. The half-life of elimination in monkeys was 1.25 h and in man 2.0 h.

Adult↗
PubMed1999

Plasma paracetamol concentrations and pharmacokinetics following rectal administration in neonates and young infants.

BACKGROUND: Despite widespread use in children pharmacokinetic data about paracetamol are relatively scarce, not the least in the youngest age groups. This study aimed to describe plasma paracetamol concentrations and pharmacokinetics of a single rectal paracetamol dose in neonates and young infants. METHODS: Perioperatively, 17 neonates and infants < or =160 days of age received one rectal paracetamol dose (mean 23.9 mg/kg (+/-4.2 mg/kg)). Blood samples were drawn at 60, 120, 180, 240, 300 and 360 min, according to the infants' weights. Plasma paracetamol concentrations were measured by a Colorometric Assay, Ectachem Clinical Chemistry Slides (Johnson & Johnson Clinical Diagsnostics). RESULTS: The plasma paracetamol concentrations were mainly below the therapeutic (i.e. antipyretic) range of 66-132 micromol/l and did not exceed 160 micromol/l in any infant. The mean maximum plasma concentration (Cmax) was 72.4 micromol/l (+/-33.5 micromol/l) and the time to Cmax, i.e. the mean Tmax was 102.4 min (_+59.1 min). The mean "apparent" terminal half-life (n=10) was 243.6 min (+/-114.1 min). CONCLUSION: The absorption of rectal paracetamol (mean dose 23.9 mg/kg, +/-4.2mg/kg) in young infants <160 days is variable and often prolonged and achieves mainly subtherapeutic plasma concentrations.

Absorption↗
PubMed1988

Site dependence of absorption-promoting actions of laureth-9, Na salicylate, Na2EDTA, and aprotinin on rectal, nasal, and buccal insulin delivery.

The site dependence of the absorption-promoting actions of laureth-9, Na salicylate, Na2EDTA, and aprotinin was studied in rats. Insulin absorption was estimated on the basis of the cumulative hypoglycemic response from 0 to 4 hr postdose, relative to that after intramuscular insulin. Insulin was administered with or without adjuvants to isolated rectal, nasal, and buccal absorption sites. Laureth-9, a nonionic surfactant which irreversibly removes membrane proteins or lipids, promoted insulin absorption from each site. The rectal, nasal, and buccal routes were 30% as effective as the i.m. route. The enhancing effects of Na salicylate and Na2EDTA, which have reversible mechanisms of permeability enhancement, were specific for rectal absorption. With these adjuvants, rectal insulin was 30-40% as effective as i.m. insulin, but nasal and buccal doses were less than 5% as effective as i.m. doses. This specificity can be at least partly explained by considering the site-to-site differences in membrane histology, although differences in pore size and membrane biochemistry might also contribute. The protease inhibitor aprotinin was ineffective in increasing insulin efficacy via each route, either alone or in combination with laureth-9.

Absorption↗