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Distribution of radioyttrium in tumor bearing nude mice.
The radionuclide 90Y was produced by the activation of yttrium nitrate in the nuclear reactor core, by the reaction 89Y (n, gamma) 90Y. The radionuclide obtained was characterized with the help of the absorption curve, decay curve and beta - and gamma - ray spectra. A slight admixture cf 89Sr was observed. The organ distribution of the radionuclide produced in tumor-bearing nude mice was established on the basis of measuring ashed tissues, since fresh as well as dried tissues exerted remarkable self-absorption effects. No selective accumulation of the radioyttrium in the tumors was observed for subcutaneously located osteosarcoma and rectal carcinoma. The highest concentrations were found in the lungs, spleen and liver. Thus, our study based on the use of the radioactive tracer 90Y does not support a recommendation to use yttrium ions as a tumor localizer, which was formerly proposed on the basis of the PIXE technique.
[Pharmacokinetics of antimicrobial agents in the elderly].
The elderly can be easily infected by certain organisms due to underlying diseases and complications. The pharmacokinetics of cefotiam, ceftriaxone, ceftizoxime, cefpodoxime proxetil, carumonam, clarithromycin, amikacin, ofloxacin and lomefloxacin in the elderly should be considered when choosing antibiotics for elderly patient with regard to infected site, causative organisms, pharmacokinetics and side effects. Pharmacokinetics in the elderly reflect potential renal dysfunction, so that t1/2 was elongated and AUC increased with age. Intravenous administration in the elderly, especially in the subjects with low body weight, the administered dose and intervals must be considered. With oral administration there was no constant tendency of the intestinal absorption.
[Absorbable synthetic mesh in abdominal surgery. Indications, operative procedures and results].
Compared to non absorbable mesh, the use of absorbable mesh offers a wider range of surgical indications. Otherwise the complications of implanted non absorbable mesh can be almost avoided. Reporting the experience of 41 own cases in abdominal surgery, indications, surgical technique and complications of absorbable mesh are demonstrated.
[Absorption and excretion of an ampicillin suppository (KS-R1) in dogs].
KS-R1, a new suppository of ampicillin (ABPC) sodium, was compared with the widely used oral ABPC and parenteral ABPC sodium in terms of absorption and excretion in mature and infant Beagle dogs. Plasma levels of ABPC in mature dogs when administered rectally with 12.5 and 25.0 mg/kg of KS-R1 reached the respective peaks of 8.0 and 13.5 micrograms/ml in 10 to 20 minutes. Thereafter, the plasma levels declined with biological half-lives of 0.72 and 0.93 hours, respectively. During the first 6 hours after administration of 12.5 mg/kg, 14.3% of the dose was excreted in urine. The relative bioavailability of KS-R1, calculated on the basis of AUC and urinary recovery after intramuscular administration of ABPC sodium, was 23.1% to 28.9%, compared with 31.1% to 50.2% in the case of oral ABPC. Plasma levels of ABPC in infant dogs rectally administered with 12.5 mg/kg of KS-R1 reached 11.9 microgram/ml in 10 minutes, and then declined with biological half-life of 1.24 hours. During the first 6 hours after rectal administration, 31.9% of the dose was recovered in the urine. The relative bioavailability of KS-R1 in infant dogs was 53.8% to 58.0%, which was better than that of mature dogs and was equal to that of oral ABPC. In the case of multiple doses of KS-R1 to mature dogs, no remarkable difference was found in concentration in plasma, and no accumulation of ABPC was demonstrated. Macroscopically, no remarkable abnormality was found at all around the sites of continuous administration.
[Methods for the evaluation of the intestinal function in the horse (author's transl)].
Diagnostic tests in horses showing signs of gastrointestinal diseases are reviewed. The use of rectal exploration is emphasized, and paracentesis as a diagnostic aid is mentioned. Special attention is given to the absorption tests as they are easy to conduct and give a relative measure of the absorptive capability of the intestinal epithelium. Glucose, D(+)-xylose and carbohydrate digestion-absorption tests are compared, and the D(+)-xylose absorption test is preferred because of the univocal curve of absorption (see Figure 1 and 2). The absorption curve in a horse suffering from alimentary lymphosarcoma (Figure 3) is shown. In assessing gastrointestinal protein loss, utilization of labelled albumin and gammaglobulins is of great importance, and the use of isotopes such as 131I and 51Cr is reviewed. Finally, a more extensive use of alkaline phosphatase as a diagnostic aid is proposed.
Rationale for using invasive thermometry for regional hyperthermia of pelvic tumors.
PURPOSE: Invasive thermometry for regional hyperthermia is time-consuming, uncomfortable, and risky for the patient. We tried to estimate the benefit/cost ratio of invasive thermometry in regional hyperthermia using the radiofrequency system BSD-2000. METHODS AND MATERIALS: We evaluated 182 patients with locally advanced pelvic tumors that underwent regional hyperthermia. In every patient a tumor-related temperature measurement point was obtained either by invasive or minimally invasive catheter measurement tracks. In the earlier period for every patient an intratumoral measurement point was decided as obligatory and intratumoral catheters were implanted intraoperatively, CT guided, or under fluoroscopy. In the later period, invasive thermometry often was avoided, if a measurement point in or near the tumor was reached by an endoluminally inserted catheter (rectal, vaginal, cervical, urethral, or vesical). For every patient side effects and complications referred to thermometry were evaluated and compared with the potential benefit of the invasively achieved temperature data. The suitability of endolumimally registered temperatures is analyzed to estimate local feasibility (specific absorption rate achieved) and local effectiveness (thermal parameters correlated with response). RESULTS: In 74 of 182 patients invasive thermometry was performed, at most CT-guided for soft tissue sarcomas and rectal recurrences. In 14 of 74 (19%) side effects such as local inflammation, pain, or abscess formation occurred that enforced removal of the catheter. However, local problems were strongly correlated with the dwell time of the catheter and nearly never occurred for dwell times less than 5 days. Fortunately, no fatal complications (e.g., bleeding or perforation) occurred during or after implantation which could be attributed to the invasive thermometry procedure. Endoluminal tumor-related temperature rises per time unit (to estimate power density) were correlated with intratumoral rises at the same patients (where both measurements were available). For a subgroup of patients pooled in two Phase II studies with rectal (n = 37) and cervical (n = 18) carcinomas thermal parameters derived from endoluminal measurements were correlated with response or local control, resp. CONCLUSIONS: If a tumor-related endoluminal temperature measurement point is available, additional invasive thermometry gives no further information to improve the power deposition pattern. For primary rectal and cervical cancer, and probably as well for prostate, bladder and anal cancer, endoluminal measurements are suitable to estimate local feasibility and effectiveness. Therefore, invasive thermometry is dispensable in the majority of patients. In some selected cases, temperature measurement in the tumor center is required to estimate the maximum temperature. In those cases, dwell time of catheters should be minimized--and it should be considered to perform invasive thermometry at the beginning (one or two heat treatments).
[Rectal administration of drugs. Fundamentals and applications in anesthesia].
Rectal administration of drugs has become a standard procedure in clinical anesthesia, most notably for anorectal induction in children. Limitations of this method include low bioavailability, a wide scatter of pharmacokinetic and pharmacological results, and poor predictability of the clinical effect in any particular patient. Historically, the rectal route has been used for the administration of smoke ("fumigation") for resuscitation and various other purposes. An ether boiler for rectal application was developed by Pirogoff as early as 1847. The pharmacokinetics of rectally administered drugs are determined by the anatomical properties of the rectum and, owing to interindividual variance, this adds to the inconsistency of absorption. Aspects that can be better controlled include the drug preparation and the vehicle, with hydrophilic solutions resulting in improved absorption. Larger volumes such as are associated with lower concentrations increase the bioavailability by enlarging the mucosal surface in contact with the drug. In contrast to the hypothetical assumption that hepatic circulation may be circumvented--thus avoiding first-pass metabolism--by direct venous drainage from the rectum into the systemic circulation via the vena cava, it has been shown that hepatic clearance is the main factor affecting bioavailability. This may be due to blood flow through anastomoses interconnecting the superior, medium and inferior rectal venous systems. Resorption from the rectum is also determined by physicochemical properties of drugs. According to the pH-partition hypothesis, only the non-ionized moiety of a compound will be available for transmucosal diffusion. The degree of ionization is a function of the local (or microclimate) milieu pH and pKa of the drug; the former is close to neutral in adults but alkaline in most children. Adsorption of feces, intraluminal degradation by microorganisms, metabolism within the mucosal cell, and lymphatic drainage do not significantly affect the fate of rectally administered drugs. In clinical practice, the rectal administration of methohexital and midazolam is an established method of premedication or induction of anesthesia in children; so far, midazolam appears to be associated with fewer complications. Ketamine has been shown to be as effective and as quick-acting as methohexital, but at least in one study its use as sole induction agent was associated with respiratory distress in some cases. However, painful diagnostic or therapeutic procedures in children may be indications for the rectal administration of ketamine. Early trials with rectally administered etomidate have been abandoned since its implication in suppression of cortisol synthesis. Narcotic analgesics in a hydrogel vehicle are effective in adult pain management.(ABSTRACT TRUNCATED AT 400 WORDS)
Excretion in insects: function of gut and rectum in concentrating and diluting the urine.
The diverse excretory systems of insects exhibit several features that appear unusual when comparisons are made with the mammalian kidney. Secretion by the Malpighian tubules of a fluid that is unlike the blood in composition, substitutes for glomerular filtration. Various reabsorptive functions, such as volume reduction, regulation of individual electrolytes, adjustment of osmotic concentration and pH regulation, which are associated with distinct renal segments in the mammalian kidney, all occur simultaneously in the rectum of terrestrial insects. Involvement of an extracellular molecular sieve in selective reabsorption is novel. As far as water transport is concerned, the rectal pads of the cockroach and locust appear to accomplish, across a single layer of cells, the same function as the countercurrent multiplier system of the mammalian kidney with its several epithelial layers. Direct absorption of water vapor in the rectum of some insects from atmospheres of low relative humidity, clearly involves quite different and unknown mechanisms. Finally, saline-water insect larvae produce hyperosmotic excreta by direct secretion of ions into the rectal lumen. They can adjust individual transport processes to form various secretions, which are appropriate to the natural waters of diverse chemical types in which these larvae thrive.
[The effect of certain active principles and excipients on the biodisposition of rectally administered acetylsalicylic acid in the rabbit].
In this work, we have studied in the rabbit, bioavailability of acetylsalicylic acid contained respectively in three forms of suppositories which are made as follows: for the first by only acetylsalicyclic acid (0.1 g); for the second by the association: acetylsalicylic acid (0.1 g) and phenobarbital (0.01 g); and for the third by acetylsalicylic acid (0.01 g), ascorbic acid (0.02 g) and thiamine chloride (0.002 g). It has been shown that ascorbic acid and thiamine chloride do not change the bioavailability of acetylsalicylic acid, while phenobarbital decreases it. In this work we have also compared two pharmaceutical forms of suppositories containing acetylsalicylic acid, ascorbic acid and thiamine chloride. In one of the two forms, acetylsalicylic acid is buffered by glycocolle. The study which consisted in giving the two forms to the rabbit rectally was concerned with the effect of glycocolle on the bioavailability of acetylsalicylic acid. It was shown that making glycocolle a buffer to acetylsalicylic acid resulted in an improved absorption as well as a delayed elimination of acetylsalicyclic acid. In this study too, we have evaluated the bioavailability of acetylsalicylic acid which is released from two types of suppositories containing respectively base witepsol W31 and base cocoa butter. In order to study this bioavailability whole suppositories were administered by rectal route to the rabbits after 24 hours of fasting (balanced crossover design with 15 days of interval after each study). Statistical analysis does not reveal any significant difference between the two forms of suppositories.
The pharmacokinetics of meprobamate following its oral and rectal administration as a series of combinations with diphenhydramine, acetylsalicylic acid, codeine and pentaerythritol tetranitrate.
Studies in human volunteers of the pharmacokinetics of the active drugs in the formulations Visano-mini (meprobamate and diphenhydramine HCl), DoloVisano (meprobamate, diphenhydramine HCl, acetylsalicylic acid and codeine phosphate) and VisanoCor (meprobamate, diphenhydramine HCl and pentaerythritol tetranitrate (PETN], have demonstrated systemic absorption of each of the drugs from all of the formulations. Bioequivalence of meprobamate is indicated despite the drug combinations involved. Some differences in diphenhydramine pharmacokinetics are, however, apparent. The bioavailability of meprobamate administered rectally to human volunteers as the marketed preparations DoloVisano Suppositories and Dolo-Visano Suppositories sine codeino, is similar to that observed following oral administration.
[Experimental study of per-rectal portal scintigraphy using 99mTc-HM-PAO].
Usefulness of per-rectal portal scintigraphy by 123I-IMP has already been admitted. We assessed whether 99mTc-HM-PAO, another agent used for cerebral blood flow scintigraphy, could be utilized for scintigraphic evaluation of the portal system. Animal experiments were carried out to evaluate the usefulness of the examination. Shunt indices obtained from per-rectal portal scintigraphy by 123I-IMP and 99mTc-HM-PAO in shunt models and shunt rate obtained by direct injection of 99mTc-MAA into the inferior mesenteric vein under laparotomy were compared. Correlation coefficient of each agent with 99mTc-MAA was 0.90 for 99mTc-HM-PAO and 0.80 for 123I-IMP. It was also noted that as larger quantity of the tracer could be administrated in 99mTc-HM-PAO than in 123I-IMP, absorption from rectum was optimum and liver extraction fraction was 94.4%. Therefore, we concluded that 99mTc-HM-PAO was useful for per-rectal portal scintigraphy.
Prolonged release of morphine alkaloid from a lipophilic suppository base in vitro and in vivo.
The in vitro release characteristics of four suppository formulations of morphine (15 mg) were investigated using the USP rotating basket dissolution apparatus. Morphine hydrochloride in polyethylene glycol (PEG), a hydrophilic suppository base, morphine alkaloid in PEG and morphine hydrochloride in Novata BBC (a lipophilic suppository base) completely released the drug within 25 min whereas, morphine alkaloid in Novata BBC (MAN) released the drug over 10 h. The absorption of the morphine hydrochloride/PEG (MHP) suppository was compared with that of a 15 mg oral solution in eight patients with malignant disease in a crossover design. Time of peak plasma morphine concentration (tmax) was similar for both preparations (1.8 +/- 1.6 h and 1.2 +/- 0.5 h, respectively; p > 0.05), showing that the MHP suppository was rapidly absorbed. The MAN and MHP suppositories were then compared in a further nine patients in a crossover design. Prolonged release of morphine from the MAN suppository was also evident in vivo as tmax (2.5 +/- 1.4 h) was significantly greater than that for the morphine hydrochloride/PEG suppository (0.7 +/- 0.3 h; p < 0.002). There was no significant difference in AUC (0-7 h) (34.5 +/- 19.2 versus 38.9 +/- 16.1 ng.h/ml, respectively; p > 0.05) indicating a similar amount of morphine absorbed. Plasma morphine concentrations were more sustained for 7 h after dosage with the MAN suppository, with lower peak (8.3 +/- 4.9 and 12.3 +/- 6.6 ng/ml, respectively) and higher 6 h plasma morphine concentrations (5.81 +/- 4.85 and 3.30 +/- 1.0 ng/ml, respectively; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Rectal electrogenic secretion--is it a putative indicator of intestinal secretory status induced by nutritional deprivation in the rat?
Intestinal secretion is enhanced by starvation in rats. The rectum from fed and 3-day-starved rats generates a basal electrogenic ion transfer (short-circuit current) in vitro which is mainly electrogenic Na+ absorption (amiloride-sensitive, 66-71%) with a small component of electrogenic chloride secretion (furosemide-sensitive, 14-22%). Bethanechol, a muscarinic agonist, caused an increase in the short-circuit current (mainly furosemide-sensitive chloride secretion) and potential difference in rectums from both fed and starved rats but the respective values for the starved animals were 100% and 64% greater. In starvation, the rat rectum is an indicator of intestinal secretory status. The result warrants investigation of human rectal electrogenic secretion in nutritional deprivation.
Water pathways across a reconstituted epithelial barrier formed by Caco-2 cells: effects of medium hypertonicity.
Caco-2 cells, originated in a human colonic cancer, are currently used as model systems to study transepithelial transports. To further characterize their water permeability properties, clone P1 Caco-2 cells were cultured on permeable supports. At confluence, the transepithelial net water movement (Jw), mannitol permeability (Ps), and electrical resistance (R) were simultaneously measured. The observed results were correlated with transmission and freeze-fracture electron microscopy studies and compared with those obtained, in similar experimental conditions, in a typical mammalian epithelial barrier: the rabbit rectum. When the serosal solution was made hypertonic (50 mM polyethylene glycol-PEG), the spontaneously observed secretory Jw rapidly reversed, became absorptive and then stabilized. Simultaneously, the R values dropped and Ps went up. In the case of the rabbit rectal epithelium, a similar treatment did not elicit significant changes in the water permeability during the first 20 min following the osmotic challenge while there was a significant increase in the transepithelial resistance. After exposure to serosal hypertonicity, several morphological modifications developed in the Caco-2 cells: Localized dilations in the intercellular spaces and vacuoles in the cytoplasm appeared. Nevertheless, most cells remained in contact and no evidence of cell shrinking was observed. Simultaneously, the tight-junction structure was more or less disorganized. The filament network lost its sharpness and "omega" figures appeared, bordering the intercellular spaces. In some cases the tight-junction network was completely disrupted. In the case of the rabbit rectum the structural modifications were completely different: Serosal hypertonicity rapidly induced cell shrinking and the opening of the intercellular spaces, with no noticeable change in the tight-junction structure.(ABSTRACT TRUNCATED AT 250 WORDS)
Plasma prednisolone levels and adrenocortical responsiveness after administration of prednisolone-21-phosphate as a retention enema.
Plasma prednisolone levels have been measured by radioimmunoassay after oral and rectal administration to healthy volunteers and to patients with idiopathic proctocolitis. The amount of prednisolone absorbed from a 20 mg retention enema given to patients with proctocolitis was about 44% of that absorbed from the same dose orally administered. Adrenocortical response to synthetic ACTH in patients receiving prolonged rectal therapy was either normal, or only slightly impaired, and this may be related to the pattern of steroid absorption rather than to the total amount absorbed.
Novel drug delivery systems for insulin: clinical potential for use in the elderly.
Diabetes mellitus is a very common disease in the elderly and its complications are responsible for excess morbidity/mortality, loss of independence and impaired quality of life. Recent studies, while not performed in the elderly, have outlined the importance of achieving tight glycaemic control in order to prevent complications. Eighty years after its discovery, subcutaneous insulin remains a major treatment for diabetes. It is used as a first-line agent in type 1 diabetes, and in type 2 diabetes when oral antihyperglycaemic agents combined with diet and exercise fail to achieve an appropriate metabolic control. To avoid injections, other routes of insulin administration have been studied, including oral, dermal and rectal routes but they were not found to be appropriate for clinical use. Buccal or nasal insulin combined with absorption enhancers proved to have interesting properties. Inhaled insulin appears to be suitable for use in patients with diabetes because of its better bioavailability and a pharmacokinetic profile that mimics the time kinetics of insulin secretion after a meal. Clinical studies were conducted among small numbers of patients with type 1 or type 2 diabetes who had been treated with subcutaneous insulin. Inhaled insulin was given three times daily, just before meals, and was combined with a bedtime subcutaneous injection of long-acting insulin. In patients with type 1 or type 2 diabetes the metabolic control achieved with inhaled insulin was similar to that obtained with a subcutaneous insulin regimen. Tolerance of inhaled insulin was good and treatment satisfaction was better than that with the subcutaneous regimen. Insulin inhalation appears to be an interesting way of insulin delivery for elderly patients with diabetes. However, no studies have been conducted in elderly patients with diabetes to assess this route's acceptability, convenience and ease of use in this particular population. In addition, it is necessary to conduct pharmacokinetic studies in the elderly because lung aging might reduce the bioavailability of inhaled insulin.
Mucoadhesive microspheres for controlled drug delivery.
Mucoadhesion is a topic of current interest in the design of drug delivery systems. Mucoadhesive micro-spheres exhibit a prolonged residence time at the site of application or absorption and facilitate an intimate contact with the underlying absorption surface and thus contribute to improved and/or better therapeutic performance of drugs. In recent years such mucoadhesive microspheres have been developed for oral, buccal, nasal, ocular, rectal and vaginal routes for either systemic or local effects. The objective of this article is review the principles underlying the development and evaluation of mucoadhesive microspheres and the research work carried out on these systems.