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PubMed1985

Theophylline versus aminophylline in rectal administration.

This study was undertaken to compare the bioavailability and the in vitro release rates of theophylline from suppositories containing either theophylline or aminophylline. The absorption of theophylline from solution and from freshly prepared suppositories formulated with Suppocire and containing anhydrous theophylline 250 mg or aminophylline 300 mg was investigated in six healthy volunteers in a blind crossover design experiment. Venous blood samples were collected before drug administration and at 1, 2, 4, 6 and 8 h afterwards. Theophylline serum levels were measured spectrophotometrically. The pharmacokinetic parameters obtained: Cmax 6.7 and 5.4 micrograms ml-1, tmax 2 h, and F8h 0.79 and 0.83 for theophylline and aminophylline, respectively, show that the two formulations are almost bioequivalent, with a slightly higher Cmax for theophylline. The in vitro release rate of theophylline from freshly prepared formulations was, however, higher (4.8 mg min-1) from aminophylline suppositories relative to those containing theophylline (2.9 mg min-1). This lack of correlation between the in vitro and in vivo results is explained by the different drug thermodynamic activities in the processes of release and membrane penetration. Thus, a better water-solubility does not automatically point to a better rectal bioavailability. The release rate of aminophylline suppositories tested after 1-year storage at room temperature dropped from 4.8 to 0.5 mg min-1. The bioequivalence of theophylline and aminophylline freshly prepared suppositories and the stability problems associated with fatty-base aminophylline suppositories indicate that the choice of ethylenediamine derivative of theophylline is an empirical development, theoretically unjustified, and must be replaced by theophylline reformulations.

Adult↗
PubMed1975

Intestinal absorption following small-bowel resection.

Proximal or distal small-bowel resection was performed on female Wistar rats. Water, glucose, electrolyte, and bile acid absorption from the perfusate was studied in bile-fistula sham-operated rats and in animals 3 months after intestinal resection, using an in-vivo recirculation perfusion system. The jejunum and caecum, but not the colon, showed adaptive increases in intestinal absorption after resection of the ileum, and supranormal bile acid absorption and enhanced glucose, water, and electrolyte absorption were demonstrated in the ileum after jejunal resection. The improvement in diarrhoea observed in some patients after right hemicolectomy may be due to compensatory changes in the residual colon; rectal mucosal thickness becomes significantly increased after right hemicoletomy.

Animals↗
PubMed1992

Cystic fibrosis: gastrointestinal complications.

An individual who has cystic fibrosis (CF) may suffer from gastrointestinal problems related to inadequately controlled intestinal absorption secondary to the pancreatic insufficiency. These include neonatal meconium ileus, distal intestinal obstruction syndrome (DIOS), constipation and acquired megacolon, rectal prolapse and rarely pancreatitis. If the intestinal malabsorption is well controlled with an effective pancreatic enzyme preparation, DIOS, constipation and rectal prolapse are infrequent. Persisting gastrointestinal symptoms should be investigated thoroughly to exclude other disorders not directly related to the cystic fibrosis; these include cows' milk intolerance, coeliac disease, giardiasis, Crohn's disease and intra-abdominal malignancy. Both appendicitis and intussusception may cause difficult diagnostic problems particularly in patients who may also have distal ileal obstruction syndrome.

Cystic Fibrosis↗
PubMed2001

Medical management of ulcerative proctitis, proctosigmoiditis, and left-sided colitis.

Ulcerative colitis distal to the splenic flexure includes disease confined to the rectum (proctitis), rectosigmoid (proctosigmoiditis or distal colitis), or extending to the descending colon or splenic flexure (left-sided colitis). These subtypes represent up to 60% to 80% of newly presenting cases of ulcerative colitis. Although these conditions are defined by the extent of colon that is affected, they also share the characteristic of being amenable to topical therapy. In general, the course of disease is milder and symptoms are less severe than in patients with more extensive colonic involvement. Nonetheless, symptoms may significantly impair patients' health-related quality of life. Treatment options include the oral and/or rectal 5-aminosalicylate (5-ASA) preparations. Rectal therapy delivering higher concentrations of active medication (5-ASA or glucocorticoids) directly to the inflamed mucosa while minimizing systemic absorption provides a highly effective and safe treatment. Oral glucocorticoids are indicated in patients who are resistant to or intolerant of 5-ASA therapy. Immunomodulators have an important role in individuals with glucocorticoid dependent or glucocorticoid refractory disease. This article reviews the clinical diagnosis and current medical management of ulcerative proctitis, proctosigmoiditis, and left-sided ulcerative colitis, including patients resistant to conventional medical therapy.

Administration, Oral↗
PubMed1994

Molecular cloning and functional expression of the bumetanide-sensitive Na-K-Cl cotransporter.

By mediating the coupled movement of Na, K, and Cl ions across the plasma membrane of most animal cells, the bumetanide-sensitive Na-K-Cl cotransporter (NKCC) plays a vital role in the regulation of ionic balance and cell volume. The transporter is a central element in the process of vectorial salt transport in secretory and absorptive epithelia. A cDNA encoding a Na-K-Cl cotransport protein was isolated from a shark rectal gland library by screening with monoclonal antibodies to the native shark cotransporter. The 1191-residue protein predicted from the cDNA sequence has 12 putative transmembrane domains flanked by large cytoplasmic N and C termini. Regulatory phosphoacceptor residues in isolated peptides are identified as Thr-189 and Thr-1114 in the predicted sequence. Northern blot analysis identified a 7.4-kb mRNA in rectal gland and most other shark tissues; a 5.2-kb mRNA was restricted to shark kidney. Homology with an uncharacterized gene from Caenorhabditis elegans and with the thiazide-sensitive Na-Cl cotransporter of flounder urinary bladder was found over most of the coding region; shorter stretches of homology were found with a C. elegans cDNA and with an uncharacterized gene of cyanobacterium. Human HEK-293 cells have been stably transfected with the shark cDNA and shown to express Na-K-Cl cotransport activity with the bumetanide sensitivity of the shark protein. The expressed transporter is functionally quiescent in the host cells and can be activated by depleting the cells of chloride.

Amino Acid Sequence↗
PubMed1990

[Analgesic activity of morphine suppository in rats].

Analgesic activity of morphine administered rectally as a suppository was investigated in rats in order to ascertain analgesic activity of morphine suppository. Morphine hydrochloride given rectally as a suppository produced analgesic activity in a dose-related manner in the tail pressure and acetic acid-induced writhing tests, and its potency (ED50 = about 17 and 0.689 mg/kg, respectively) was approximately twice that of morphine hydrochloride administered orally as an aqueous solution. The analgesic action was as durable as that of oral morphine, but its onset was faster. The plasma and brain levels of morphine reached peak until 30 min after rectal administration of morphine suppository, and these time-courses approximately corresponded with that of the analgesic action. These results suggest that morphine given rectally to rats as a suppository produces analgesic action equivalent or superior to orally administered morphine after absorption from the rectum.

Analgesics↗
PubMed1983

Performance and digestion by calves from limestone added to milk replacers containing soy protein concentrate.

Sixteen male Holstein calves were fed milk replacers containing milk protein or 50% of the protein from soy protein concentrate for study of limestone as a buffer in the small intestine. Experimental diets were: A) 19% of crude protein as milk protein; B) same as A but containing .8% limestone; C) 19% crude protein, 9.5% milk protein, and 9.5% soy protein; and D) same as C but containing .8% limestone. Milk replacers were reconstituted with water to 14% solids and fed at 8, 9, 10, 11, 12, and 12% body weight from 1 to 6 wk of age. Calves were fed twice daily, and clean fresh water was available at all times. Soy protein concentrate in the replacer resulted in 20% lower weight gains, lower dry matter and protein digestibilities. Apparent crude protein retention also was reduced, but intake of nutrients, feed efficiencies, fecal scores, and rectal temperatures were not different between protein sources. Limestone did not change any of these measurements. Xylose absorption tests at 3 and 6 wk of age showed differences from age but not treatment. Analysis of digesta from different sections of the gut of 6-wk-old calves sacrificed 6 h after feeding revealed that pH throughout the small intestine was above 6 for both proteins, which may explain the ineffectiveness of added limestone. Compared to milk protein, soy protein concentrate produced a lower pH in the large intestine and feces.

Animals↗
PubMed1993

Granulomatous enteritis and cutaneous arteritis in a horse.

A 5-year-old Quarter Horse mare was examined because of weight loss of 2 months' duration. The horse was anemic and in poor body condition, and had several areas of cutaneous ulceration, including areas on the muzzle and distal portion of the limbs. Histologic examination of a rectal mucosa biopsy specimen revealed a lymphoplasmacytic infiltrate in the lamina propria mucosa. Results of a glucose absorption test were suggestive of malabsorption. Histologic examination of a biopsy specimen from the cutaneous lesions revealed pronounced arteritis, and weak, patchy immunofluorescent staining for immunoglobulins at the basement membrane. The horse was treated with prednisone, but did not improve, so the horse was humanely destroyed. Necropsy revealed granulomatous enteritis. This case identified an unusual combination of clinical problems and suggests further evidence for similarities between equine granulomatous enteritis and regional enteritis in human beings.

Animals↗
PubMed1998

Possibility of partial absorption of nicardipine by routes other than the hepato-portal system after oral administration in rats.

The systemic availability of nicardipine after different routes of administration has been examined in rats, with particular attention to differentiating oral absorption from intestinal and hepatic metabolism. The quantities of nicardipine and its metabolite were determined by capillary column gas chromatography. A linear relationship was shown between the hepatic first-pass effect and dose after hepato-portal administration of nicardipine; the hepatic first-pass effect was calculated to be approximately 80%. However, the availability after oral and rectal administration was found to be more than twice that observed after hepato-portal administration. Partial avoidance of the hepatic first-pass effect after oral and rectal administration are estimated to be 37.3% and 35.2%, respectively, assuming that all absorbed molecules pass through the liver. These findings suggest that the absorption of nicardipine after oral administration also occurs by routes other than the hepato-portal system.

Administration, Oral↗
PubMed2005

Population pharmacokinetics of pyrazinamide in elephants.

This study was undertaken to characterize the population pharmacokinetics (PK), therapeutic dose, and preferred route of administration for pyrazinamide (PZA) in elephants. Twenty-three African (Loxodonta africana) and Asian (Elephas maximus) elephants infected with or in contact with others culture positive for Mycobacterium tuberculosis were dosed under treatment conditions. PZA was dosed daily at 20-30 mg/kg via oral (fasting or nonfasting state) or rectal (enema or suppository) administration. Blood samples were collected 0-24 h postdose. Population PK was estimated using nonlinear mixed effect modeling. Drug absorption was rapid with T(max) at or before 2 h regardless of the method of drug administration. C(max) at a mean dose of 25.6 (+/-4.6) mg/kg was 19.6 (+/-9.5 microg/mL) for PZA given orally under fasting conditions. Under nonfasting conditions at a mean dose of 26.1 +/- 4.2 mg/kg, C(max) was 25% (4.87 +/- 4.89 microg/mL) and area under concentration curve (AUC) was 30% of the values observed under fasting conditions. Mean rectal dose of 32.6 +/- 15.2 mg/kg yielded C(max) of 12.3 +/- 6.3 microg/mL, but comparable AUC to PZA administered orally while fasting. Both oral and rectal administration of PZA appeared to be acceptable and oral dosing is preferred because of the higher C(max) and lower inter-subject variability. A starting dose of 30 mg/kg is recommended with drug monitoring between 1 and 2 h postdose. Higher doses may be required if the achieved C(max) values are below the recommended 20-50 microg/mL range.

Administration, Oral↗
PubMed1996

Bioavailability of the antiemetic metopimazine given as a microenema.

The absorption of the antiemetic metopimazine (MPZ) given as a single dose of (a) 40 mg microenema, (b) 40 mg orally and (c) 10 mg as a 60 min i.v. continuous infusion was investigated in six healthy volunteers. Blood samples were drawn and the serum concentrations of MPZ and its acid metabolite were measured. The bioavailability of MPZ given orally and as enemas was 22.3 and 19.5% respectively. Partial avoidance of hepatic first pass metabolism was seen with the enemas, which in contrast to suppositories, seems to represent a reliable form of rectal administration.

Administration, Oral↗
PubMed1998

Comparative clinical pharmacokinetics of single doses of sumatriptan following subcutaneous, oral, rectal and intranasal administration.

Sumatriptan, a 5-HT1 receptor agonist active for the acute treatment of migraine, is currently available as subcutaneous injection and oral tablets. Rectal or intranasal formulations may offer advantages over those marketed. This study compared the pharmacokinetics of sumatriptan via all four routes. Usual absorption parameters were described and the rate of absorption was assessed using deconvolution technics. There were no statistical differences between the non-parenteral routes for tmax or Cmax/AUCinfinity. However, Cmax and AUCtmax were statistically greater with the suppository than with the tablet, but there was no difference between intranasal and oral routes. The highest rate of absorption occurred earlier with the intranasal than with the oral route. Relative to the subcutaneous route, the bioavailability for the suppository was greater than for intranasal spray and oral tablet. The amount of sumatriptan excreted in the urine unchanged was similar for all routes. Sumatriptan in this study was well tolerated.

Administration, Intranasal↗
PubMedDate not supplied

Absorption of theophylline from the small and large intestine of the neonatal piglet.

In this study, the newborn piglet model was used to assess theophylline absorption from various areas of the GI tract. 13 piglets, ages 9-14 days, had their intestines surgically exposed. Four segments of equal length (jejunum, ileum, right colon and left colon) were simultaneously perfused with a saline solution containing [3H]-polyethylene glycol 4000 to measure water shifts and theophylline at a total dose of 5 mg/kg, a typical neonatal dose. Absorption of theophylline, appearance in serum, and the effects of the drug on water and electrolyte movement in the intestinal segments were monitored. Serum concentrations of theophylline after an intravenous and oral dose were also studied in 2 piglets. The data showed excellent absorption of the drug from all intestinal segments studied (jejunum 0.97 +/- 0.16, ileum 0.7 +/- 0.13, right colon 0.7 +/- 0.13, and left colon 0.88 +/- 0.19 micrograms/cm/min), despite a concomitant secretion of sodium chloride and water. No statistical differences in absorptive capacity were seen among segments. The results suggest that as little as 100 cm of residual intestine could, theoretically, absorb a 5 mg dose of theophylline if presented slowly. These findings have ramifications for neonates who may receive theophylline orally or rectally.

Animals↗
PubMed2000

Pharmacokinetics of orally administered camptothecins.

Phase I trials of oral camptothecins, including camptothecin (CPT) and irinotecan (CPT-11), have reported substantial interpatient variability in systemic exposure, which could result in suboptimal antitumor activity in some patients or enhanced risk for toxicity in others. This investigation evaluates the contribution of intestinal absorption and first-pass metabolism in the disposition of oral CPT and CPT-11, respectively. The transport of CPT in Caco-2 cell lines (validated model of intestinal drug transport) was concentration dependent and saturable (Vmax: 34 x 10(-5) cm/sec and Km: 20 microM), and was temperature dependent with an activation energy (Ea) of 11.7 kcal/mole. Cumulatively, this data was indicative of carrier-mediated intestinal transport. In addition, a reduction of transport in the presence of sodium azide plus deoxyglucose suggested ATP dependence. Thus, variable expression and availability of intestinal transporters could contribute to the observed wide variability in the exposure to oral CPT. CPT-11 is hydrolyzed by the ubiquitous enzyme carboxyl esterase to active SN-38, and first-pass metabolism of oral CPT-11 would include both intestinal and hepatic hydrolysis. Incubation of CPT-11 with S9 fractions of human liver and intestinal tissues resulted in variable rates of formation of SN-38. The mean (+/- SD) specific activities (pmoles/min/mg) were: liver (8.57 +/- 10.4, n = 8), duodenum (5.06 +/- 3.7, n = 4), jejunum (6.44 +/- 2.8, n = 5), ileum (4.81 +/- 2.4, n = 5), colon (1.93 +/- 1.5, n = 6), and rectum (0.82, n = 1). Interestingly, there was a decrease in SN-38 formation by tumor tissue compared to matched normal liver and colon tissues. Therefore variable first-pass metabolism could contribute to the substantial differences in the systemic exposures to CPT-11 and SN-38 in patients receiving oral CPT-11.

Administration, Oral↗