Rectally administered prednisolone--evidence for a predominantly local action

Urinary excretion profile of prednisolone and prednisone after rectal administration: significance in antidoping analysis

The rectal administration of glucocorticoids, as well as any injectable, and oral ones, is currently prohibited by the World Anti-Doping Agency when occurs "in competition". A reporting level of 100 ng/mL for prednisolone and 300 ng/mL for prednisone was established to discriminate the allowed and the prohibited administration. Here, the urinary excretion profiles of prednisone and prednisolone were evaluated in five volunteers in therapy with glucocorticoid-based rectal formulations containing prednisone or prednisolone caproate. The urinary levels of the excreted target compounds were determined by LC-MS/MS following the procedure validated and currently in use in our laboratory to detect and quantitate glucocorticoids in urine. Predictably, the excretion trend of the analytes of interest were generally comparable to those obtained after oral administration, even if the excretion profile showed a broad inter-individual variability, with the absorption rate and the systemic bioavailability after rectal administration being strongly influenced by the type of formulations (suppository or rectal cream, in our case) as well as the physiological conditions of the absorption area. Results showed that the target compounds were detectable for at least 30 hours after drug administration. After suppository administration, prednisolone levels reached the maximum after 3 hours from drug administration, and then dropped below the reporting level after 15-21 hours; prednisone reached the maximum after 3 hours from drug administration, and then dropped below the reporting level after 12-15 hours. After cream administration both prednisone and prednisolone levels remained in a concentration below the reporting level throughout the entire monitored period.

Advances in Colonic Drug Delivery

Targeting drugs and delivery systems to the colonic region of the gastrointestinal tract has received considerable interest in recent years. Scientific endeavour in this area has been driven by the need to better treat local disorders of the colon such as inflammatory bowel disease (ulcerative colitis and Crohn's disease), irritable bowel syndrome and carcinoma. The colon is also receiving significant attention as a portal for the entry of drugs into the systemic circulation. A variety of delivery strategies and systems have been proposed for colonic targeting. These generally rely on the exploitation of one or more of the following gastrointestinal features for their functionality: pH, transit time, pressure or microflora. Coated systems that utilise the pH differential in the gastrointestinal tract and prodrugs that rely on colonic bacteria for release have been commercialised. Both approaches have their own inherent limitations. Many systems in development have progressed no further than the bench, while others are expensive or complex to manufacture, or lack the desired site-specificity. The universal polysaccharide systems appear to be the most promising because of their practicality and exploitation of the most distinctive property of the colon, abundant microflora.

The short-term effects of Eudragit-L-coated prednisolone metasulphobenzoate (Predocol) on bone formation and bone mineral density in acute ulcerative colitis

BACKGROUND

The aetiology of bone loss in ulcerative colitis is multifactorial, but corticosteroid treatment is an important risk factor. A novel formulation of Eudragit-L-coated prednisolone metasulphobenzoate (Predocol) has been developed, in order to deliver high mucosal levels of prednisolone within the colon but with little systemic absorption. The aim of this study was to investigate its efficacy, and short-term effects on bone formation and bone mineral density.

METHODS

In a 12-week longitudinal study 13 patients with active colitis were treated with a reducing dose of Predocol. Disease activity scores were recorded and the bone formation marker osteocalcin was measured before, during and after treatment, with hip and spine bone mineral density assessed at baseline and after treatment.

RESULTS

Eleven of the 13 patients completed the study. Compared with baseline, disease activity scores improved significantly after 4 weeks [difference in means, 6.9; 95% confidence interval (CI), 5.2, 8.7; P < 0.0001] and 12 weeks (difference in means, 5.7; 95% CI, 3.3, 8.2; P < 0.0001) of treatment. Osteocalcin did not fall compared with baseline [16.91 mg/l (95% CI, 12.70, 21.12)], after 4 weeks [13.67 mg/l (95% CI, 8.72, 18.60)] (difference in means, 3.25; 95% CI, 2.37, 8.87; P = 0.23) or 12 weeks [23.91 mg/l (95% CI, 16.10, 31.74)] (difference in means, 13.23; 95% CI, 2.45, 16.48; P = 0.13) of treatment. Similarly, bone mineral density at the hip [0.99 g/cm (95% CI, 0.90, 1.09)] did not change after 12 weeks of treatment [1.00 g/cm (95% CI, 0.89, 1.11)] (difference in means, 0.01; 95% CI, 0.25, 0.34; P = 0.74). Spine bone mineral density did not fall from pre-treatment levels [1.20 g/cm (95% CI, 1.11, 1.30)] after 12 weeks [1.19 g/cm (95% CI, 1.10, 1.29)] (difference in means, 0.01; 95% CI, 0.004, 0.01; P = 0.26).

CONCLUSIONS

These results confirm that Predocol is effective treatment for acute ulcerative colitis and short courses of the steroid have no adverse effects on bone formation and bone mineral density. The encouraging results from this study suggest that Predocol may be a significant advance in preventing corticosteroid induced bone loss in ulcerative colitis.

Inflammatory bowel disease

IBD results from the interaction of genetic and environmental factors (e.g., smoking). Clinical suspicion is the key to diagnosis, which then rests on colonoscopy, histopathological examination of multiple biopsy specimens, small bowel barium radiology and faecal examination. The primary goal of treatment is remission--histological in ulcerative colitis and symptomatic in Crohn's disease. Treating active disease and maintaining remission require different approaches. For active disease, short term corticosteroids are the mainstay of treatment, while immunosuppressive drugs are important in chronically active disease. For maintenance, mesalazine-delivering drugs and immunosuppressive agents are efficacious in both ulcerative colitis and Crohn's disease; patients with Crohn's disease should not smoke.

Review article: issues in oral administration of locally acting glucocorticosteroids for treatment of inflammatory bowel disease

Inflammatory bowel diseases are treated in some cases by local administration of anti-inflammatory drugs. Local delivery of drugs in the colon following oral administration may lead to improved efficacy/side-effect profiles and may improve patient compliance. This review covers a number of issues important in the design of oral delivery systems of glucocorticosteroids for local therapy of colonic inflammation. The choice of specific glucocorticosteroids is based on the drug's physicochemical and pharmacological properties. The conditions under which an orally administered glucocorticosteroid (or other drug) must be delivered to treat ulcerative colitis are also discussed. These conditions include variations in local pH, transit throughout the gastrointestinal tract, the potential role of gut microflora, and drug dissolution in both the healthy and diseased large intestine. The effective delivery of topically-active glucocorticosteroids in ulcerative colitis and Crohn's colitis patients is complex, but if successful could improve their usefulness.

Beclomethasone dipropionate enemas versus prednisolone sodium phosphate enemas in the treatment of distal ulcerative colitis

AIM

To compare beclomethasone dipropionate 3 mg/60 mL enema (BDP) and prednisolone sodium phosphate 30 mg/60 mL enema (PP) once daily in patients with active distal ulcerative colitis.

METHODS

One hundred and fifty-seven patients were enrolled in a multicentre, 4-week, randomized, double-blind trial. Patients were assessed at baseline, 2 and 4 weeks.

RESULTS

Both treatment groups showed statistically significant improvement of clinical activity after 2 and 4 weeks. Endoscopy and biopsy showed a reduction in the activity score at the end of the treatment period in both groups. No statistically significant difference was observed between the two treatment groups. After 4 weeks, 29% of patients in the BDP group and 25% in the PP group were considered to be in clinical remission; an improvement was observed in 40% of patients on BDP and in 47% on PP. Mean morning plasma cortisol levels showed a slight but significant reduction in the PP group, while the ACTH test showed that neither drug interfered with the hypothalamic-pituitary-adrenal (HPA) axis function. No significant changes were observed in the laboratory tests. Finally, there was a low incidence of adverse events in both groups.

CONCLUSIONS

It is concluded that, in the topical treatment of active distal ulcerative colitis, BDP 3 mg enemas are as efficacious as PP 30 mg enemas, without interference with the HPA axis.

Innovations in topical therapy

Topical therapy can be considered the standard treatment for distal ulcerative colitis. The group of drugs of first choice are the aminosalicylates which are effective in inducing remission in acute disease as well as in preventing relapse. Corticosteroids appear to be slightly less effective and have no proven benefit in maintenance therapy. With new topical steroids, such as budesonide, systemic effects can be minimized. The major role of corticosteroids is to complement aminosalicylates, when necessary. The new topical compounds appear to be especially valuable when there is a long-term requirement for corticosteroids. With the vast majority of patients obtaining remission with standard treatment, it is difficult to make the case for alternative substances. Short-chain fatty acids, local anaesthetics and bismuth compounds seem to be the most promising innovations in topical therapy although their equivalence or even superiority to mesalazine has not been established.

Inflammatory bowel disease management. Some thoughts on future drug developments

This article is intended to stimulate thought and focus on those areas where we feel advances in drug therapy for inflammatory bowel disease may occur. It is not an extensive review of current practice, although this is considered where it is thought to be pertinent to future developments. There are several excellent reviews of current practice which we do not attempt to repeat, nor do we give a comprehensive set of references, but cite well referenced reviews where necessary. New therapeutic developments should ideally stem from an understanding of the cause of pathogenesis of a condition; alternatively, established therapies may be modified or used as a basis for progress. Since the causes of both ulcerative colitis and Crohn's disease remain unknown, most forward thinking on drug development must come from current practice, but remain open to novel approaches. Our thoughts on possible future treatments for inflammatory bowel disease are somewhat selective, and because of their speculative nature are unlikely to coincide with those of others-only the future will reveal genuine advances as they become incorporated into established practice.

Rectal steroids suppress bone formation in patients with colitis

BACKGROUND

The aetiology of bone loss in inflammatory bowel disease is multifactorial, but oral corticosteroids are an important contributory factor. Rectally administered steroids are widely used in patients with distal disease, but very little is known about their effect on bone metabolism. The aim of this study was to investigate the effect of a standard course of rectal prednisolone on biochemical markers of bone turnover.

METHODS

In a longitudinal study of 10 patients, biochemical markers of bone turnover were measured before, during and after treatment with prednisolone metasulphobenzoate (Predfoam, Pharmax Ltd) 20 mg twice daily for 2 weeks. Bone formation markers measured were serum osteocalcin (BGP), bone-specific alkaline phosphatase (BALP) and procollagen carboxy-terminal propeptide (PICP). Urinary deoxypyridinoline (dPyr) was measured to assess bone resorption.

RESULTS

Disease activity scores improved during treatment (difference in mean Powell-Tuck score = 2.3 (+/-13.1), 95% CI: 0.11-4.48, P = 0.04). There was a significant fall in BALP (P = 0.02) during treatment, and a rapid but non-significant fall in BGP (P = 0.19). PICP (0.42), and urinary dPyr (0.30) did not change significantly during treatment.

CONCLUSIONS

Following a standard 2-week course of rectal prednisolone metasulphobenzoate, we observed a significant fall in bone-specific alkaline phosphatase activity. These results suggest that bone formation is suppressed in patients with distal colitis treated with pharmacological doses of rectal steroids.

Newer treatments for inflammatory bowel disease

Despite intense investigative efforts, the causes of ulcerative colitis and Crohn's disease remain elusive. The mainstay of medical therapy focuses on inhibition of the effects of the inflammatory mediators operant in inflammatory bowel disease because the causes of these two chronic disorders are unknown. During recent years, the physician's armamentarium for medical treatment of inflammatory bowel disease has increased substantially. In this article, the current standard medical therapies available for treatment of patients with inflammatory bowel disease are reviewed along with their efficacy; the side effects and status of other investigative drugs also are reviewed.

Topical anticolitic efficacy and selectivity of the glucocorticoid budesonide in a new model of acetic acid-induced acute colitis in the rat

AIMS

To study the effect of local or parenteral administration of the glucocorticoid budesonide in the acetic acid-induced colitis model in the rat.

METHODS

Colitis was induced in an exteriorized colonic segment by administration of 4% acetic acid for 15 s. Four days later, this colonic segment with colitis was examined using a morphological scoring system, and measurements of myeloperoxidase activity and of plasma exudation into the colonic segment. The experimental colitis showed morphological similarities to human ulcerative colitis, with 3-fold increase in myeloperoxidase activity and 6-fold increase in the plasma exudation. Budesonide in different doses administered for 3 days, starting one day after acetic acid instillation, prevented the development of colitis in a dose-dependent manner. The best effect of budesonide on the morphological score was achieved after local treatment at a dose of 10(-5) M twice daily (76% reduction compared with a control colitis group) and parenteral treatment with 0.75 mg/kg (80% reduction). These doses also normalized myeloperoxidase activity and significantly reduced the plasma exudation. The systemic effects of the drug were most pronounced in the group treated with parenteral budesonide. This group showed the greatest reduction in body weight and a significant reduction of the weight of adrenal glands and spleen (as compared to controls). Thymus weight in animals treated systemically was significantly lower than in locally treated animals. In the group treated with local budesonide the weight of adrenals was reduced. However, the weights of spleen and thymus were not reduced and the reduction of the body weight was even less than in the control group.

CONCLUSION

Local treatment with budesonide at a dose of 10(-5) M (0.17 mg/kg if completely absorbed, but only 0.03 mg/kg with 15% bioavailability on colonic application) was as effective as parenteral treatment at a dose of 0.75 mg/kg in the attenuation of acetic acid-induced colitis in the rat, but resulted in minor systemic side-effects.

Pharmacokinetics of budesonide enema in patients with distal ulcerative colitis or proctitis

Pharmacokinetic data obtained after one dose of a 2-mg budesonide enema were compared with data obtained after the last dose of four weeks of daily treatment in 24 patients with active distal ulcerative colitis or proctitis. This open multicentre study involved 28 eligible patients. Sigmoidoscopy and biopsy scores improved significantly (P < 0.002) during the four-week treatment period. Maximal plasma concentration (Cmax) of budesonide was 2.1 nmol/L 1.3 h after the first dose and 2.5 nmol/L 1.2 h after the last dose; the difference was not significant. The area under the curve (AUC) of plasma concentration vs. time was after the first dose 9.7 nmol h/L and after the last dose 11.6 nmol h/L (P < 0.03). The small increase in AUC may be attributed to improved absorption. During the last dose interval, minimal plasma concentration was below the limit of quantitation in most subjects. The Cmax and AUC of budesonide increased slightly after four weeks of treatment, but budesonide did not accumulate. Mean morning plasma cortisol values did not change significantly during treatment (P = 0.083), although a small change in cortisol levels between the first visit (pre-treatment) and last visit was positively correlated to the Cmax of budesonide measured at the last visit (P = 0.012).

Review article: topical corticosteroids in inflammatory bowel disease

It would be ideal to treat inflammatory bowel disease with topical corticosteroids that are either not absorbed through the mucosa, or have a substantial first-pass hepatic metabolism. The topical use of hydrocortisone, prednisolone-21-phosphate or betamethasone is often associated with systemic side-effects. Newer corticosteroid preparations (prednisolone metasulphobenzoate, tixocortol pivalate, fluticasone propionate, beclomethasone dipropionate and budesonide) are usually associated with minimal systemic corticosteroid activity. This article reviews the clinical activity and safety of these newer preparations.

Spread and distribution of 5-ASA colonic foam and 5-ASA enema in patients with ulcerative colitis

Rectal treatment with enemas, foams, and suppositories is the most efficient method of delivering an adequate quantity of locally active drugs to the distal colon. In a pilot study carried out by colonoscopy in four patients, it was observed that 4 g 5-ASA in 20 ml foam spread up or beyond the splenic flexure and more extensively than 2 g 5-ASA in 10 ml foam. Therefore we have undertaken a study in order to compare by scintigraphy the colonic distribution of 4 g 5-ASA foam versus 4 g 5-ASA in 100 ml liquid enemas in 10 patients with ulcerative colitis using a crossover randomized design. Both preparations were labeled with 100 MBq [99mTc]sulfur colloid before administration. Anterior scans were taken at intervals for 4 hr. Activity, expressed as a percentage of total radioactivity, was measured in the rectum, sigmoid, descending, transverse, and ascending colon. Six patients had the same extent of spread with the two formulations; in three patients with foam and in one patient with enema a greater spread was observed. The foam reached the upper limit of disease in all cases, while enema failed in two cases. The maximum spread with foam was observed within 30 min in nine of 10 patients compared with seven of 10 after enema. Compared to enema, foam distributes more uniformly and seems to persist longer in the descending and sigmoid colon. The 5-ASA colonic foam shows some more favorable characteristics than enema for the local treatment of left-sided ulcerative colitis.

New therapeutic agents in the treatment of inflammatory bowel disease

Despite intense investigation, the etiology of inflammatory bowel disease (IBD) remains unknown. Recent studies with new therapeutic agents provide insight into the pathogenesis of IBD through analysis of the clinical response to pharmacologic agents whose mechanism of action is understood. Until new agents are established, IBD will be treated with conventional drugs directed toward modifying the inflammatory responses responsible for gastrointestinal mucosal damage. Sulfasalazine, mesalamine (5-aminosalicylic acid), and corticosteroids will continue to be the mainstay of therapy for the foreseeable future. Antibiotics such as metronidazole and immunosuppressants such as 6-mercaptopurine and methotrexate are useful in Crohn's disease and ulcerative colitis in selected cases. Many new exciting agents are being investigated and show encouraging results in the treatment of IBD. This article reviews the agents used in IBD with an emphasis on new therapeutic agents.

Drug management of ulcerative colitis

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Medical management of severe inflammatory disease of the rectum and distal colon: non-nutritional aspects

Rectal bleeding is the cardinal symptom in patients with inflammation of the rectum, and initial management must be directed at establishing an underlying diagnosis. In many patients in the Western World this will be idiopathic inflammatory bowel disease, although in all cases other causes such as infection must be excluded. Idiopathic proctitis is usually due to either ulcerative colitis or Crohn's disease, and in both conditions corticosteroids, either systemic or topical, provide the mainstay of treatment. The 5-aminosalicylic acid drugs are helpful in both acute and maintenance treatment, again given either systemically or topically, while metronidazole is of value in patients with Crohn's disease. In those with refractory proctitis alternative agents such as azathioprine, immunomodulating drugs and barrier agents may be useful. Severe inflammation of the rectum secondary to pelvic irradiation will also usually respond to topical steroid therapy, although sucralfate enemas may be equally successful; in resistant cases other treatments may be needed. Infective proctitis, when diagnosed, may require treatment with specific antimicrobial agents.

An Eudragit-coated prednisolone preparation for ulcerative colitis: pharmacokinetics and preliminary therapeutic use

Prednisolone metasulphabenzoate, a steroid with poor colonic absorption, was coated with the pH-dependent acrylic resin Eudragit S, as a means of delivering an orally administered preparation to the proximal colon. The therapeutic potential of delivering this steroid with potentially less systemic side-effects to the proximal colon was assessed in extensive ulcerative colitis. Plasma and urine prednisolone profiles in 6 healthy volunteers confirmed minimal absorption from Eudragit S-coated prednisolone metasulphabenzoate compared to prednisolone acetate: peak plasma prednisolone concentrations 29 +/- 21 ng/ml vs. 570 +/- 185 ng/ml (P less than 0.01), area under curve measurements 204 +/- 214 vs. 2724 +/- 1236 ng.h/ml (P less than 0.01). Prednisolone metasulphabenzoate coated with Eudragit S (30-60 mg daily) was then administered for 12 weeks to 12 patients with colonoscopically proven extensive ulcerative colitis in relapse. Symptoms, sigmoidoscopic appearances and rectal histological abnormalities all improved during therapy. Complete clinical remission occurred in 7 patients, a partial response in 2 patients and no response in 3 patients. Cortisol responses to tetracosactrin demonstrated no significant adrenal suppression following treatment. Eudragit S-coated prednisolone metasulphabenzoate may be a useful treatment for extensive ulcerative colitis, without risk of systemic steroid side-effects.

A steroid enema, budesonide, lacking systemic effects for the treatment of distal ulcerative colitis or proctitis

The aim of this study was to evaluate whether budesonide enema (2 mg/100 ml) had a significantly better effect than placebo in the treatment of distal ulcerative colitis or proctitis. The trial was of controlled, randomized, double-blind design and included 41 treated patients. The treatment time was 4 weeks, with revisits after 2 and 4 weeks. If no improvement was seen, the patient could be switched over to open-label therapy with budesonide enema. Sigmoidoscopy, histology, blood chemistry, and diary cards were used for estimating the effect of treatment. The results showed that budesonide was superior to placebo. Sigmoidoscopy and biopsy scores improved significantly (p less than 0.01) in budesonide-treated patients compared with placebo. Significantly more patients switched over to open budesonide treatment in the placebo group owing to lack of efficacy compared with budesonide (p less than 0.001). No drug-related adverse experiences occurred, and there was no decrease in endogenous morning plasma cortisol levels. It is concluded that budesonide enema appears to be an effective and safe treatment for distal ulcerative colitis and proctitis.

Budesonide enema in distal ulcerative colitis. A randomized dose-response trial with prednisolone enema as positive control. The Danish Budesonide Study Group

The effect of budesonide, 1, 2, and 4 mg/100 ml in daily enemas, on active distal ulcerative colitis was compared with that of prednisolone disodium phosphate enemas, 25 mg/100 ml, in a multicentre, randomized, group-comparative trial. A total of 146 patients with active disease were treated for 2 weeks. Data from 139 were valid for statistical analyses. Bowel habits, proctoscopy findings, and histologic pictures were evaluated, and plasma cortisol was determined for measurement of influence on the hypothalamic-pituitary-adrenal axis. Clinical symptoms and proctoscopy findings improved within all treatment groups. The improvement of these effect variables tended to be less after treatment with the lowest dose of budesonide, 1 mg/100 ml, than after the other treatments. Plasma cortisol did not change in any of the budesonide groups, whereas a mean reduction of 30% (P = 0.07) was observed after prednisolone. It can be concluded that budesonide enemas of 2 mg/100 ml constitute an attractive alternative to prednisolone enemas for topical treatment of distal ulcerative colitis.

Pharmacokinetics of rectal drug administration, Part II. Clinical applications of peripherally acting drugs, and conclusions

Part I of this article, which appeared in the previous issue of the Journal, covered general considerations, the physiology of the rectum, spreading of drugs into the colon, rectal absorption, partial avoidance of first-pass elimination, rate-controlled rectal delivery of drugs, irritation of the rectal mucosa and clinical applications of rectal administration, and discussed centrally acting drugs. In Part II, this discussion is extended to drugs which act peripherally and to methods of enhancing rectal drug absorption. The overall summary appeared in Part I.

Relative anti-inflammatory effect of oral dexamethasone-beta-D-glucoside and dexamethasone in experimental inflammatory bowel disease in guinea-pigs

The relative anti-inflammatory effect of dexamethasone and a prodrug, dexamethasone-beta-D-glucoside, has been assessed in guinea-pigs with experimentally-induced inflammatory bowel disease (IBD). The glucoside prodrug is designed to reach the large intestine following oral administration. The active agent is liberated when the prodrug is hydrolysed by glycosidases of colonic bacteria. Guinea-pigs were administered degraded carrageenan in their drinking water to produce experimental IBD. Starting on day 15, dexamethasone (1.3 mumol kg-1) or dexamethasone-beta-D-glucoside (1.3 or 0.65 mumol kg-1) was administered by gastric intubation once daily for 5 days. Relative to control animals, the drug and prodrug treatments significantly (P less than 0.05) reduced the total number of caecal ulcers. While there was no difference statistically between the drug and prodrug treatments, the data suggest that a lower dose of dexamethasone, administered as its glucoside prodrug, could reduce side-effects without reduced efficacy. These results support the hypothesis that localized delivery of dexamethasone to the large bowel can improve pharmacotherapy of IBD by reducing the side-effects associated with corticosteroids.

Colon-specific delivery of dexamethasone from a glucoside prodrug in the guinea pig

Dexamethasone-beta-D-glucoside is a potential prodrug for colonic delivery of the antiinflammatory agent, dexamethasone. The ability of this prodrug to deliver dexamethasone selectively to the colon depends not only on its being slowly absorbed from the alimentary canal, but also on its having chemical and enzymatic stability in the stomach and small intestine. Once reaching the large bowel, it should be quantitatively hydrolyzed to release the active agent. The potential of dexamethasone-beta-D-glucoside for colon-specific delivery of dexamethasone is assessed by determining the rates of its hydrolysis down the alimentary canal of the guinea pig, an animal in which an inflammatory bowel disease model has been developed. The hydrolytic activity is examined in tissues and luminal contents of the stomach, proximal and distal segments of the small intestine, cecum, and colon. For the tissues, the greatest hydrolytic activity is in the proximal small intestine, while the stomach, cecum, and colon have only moderate activity. In contrast, the contents of the cecum and colon show greater activity than the contents of the small intestine and stomach. The luminal contents retained beta-glucosidase activity even after repeated centrifugation and resuspension in a buffer. The activity was unaffected by homogenization. These observations suggest that hydrolytic activity is associated with enzymes located on the surface of luminal cells. The movement and hydrolysis of dexamethasone-beta-D-glucoside down the gastrointestinal tract of the guinea pig are also examined. About 20 to 30% of an oral dose appears to reach the cecum. Here the prodrug is rapidly hydrolyzed to the active drug. From intravenous administration of the prodrug and drug, it is apparent that dexamethasone-beta-D-glucoside is poorly absorbed in the gastrointestinal tract (bioavailability, less than 1%). There is a ninefold selective advantage for delivery of dexamethasone in cecal tissues in the guinea pig under the conditions of this experiment. Thus, there is a potential for a decrease in the usual dose and a concomitant reduction in the systemic exposure to dexamethasone. Because humans have much less glucosidase activity in the small intestine, even greater site-selective delivery to the cecum and colon is expected.

Inflammatory bowel disease

An increasing number of options are available for the treatment of inflammatory bowel disease; the selection depends on the extent and severity of the disease. Experience with sulfasalazine and corticosteroids has led to a proliferation of 5-aminosalicylic acid (5-ASA) compounds and experimentation with alternative corticosteroid preparations. Given rectally 5-ASA is particularly effective in the treatment of distal ulcerative colitis, and experience is accumulating with several oral formulations. Metronidazole is useful in some cases, and immunosuppressive agents have a role in some patients with chronic refractory disease. A variety of measures, such as nutritional therapy, surgery and psychosocial support, are important elements of therapy. Further therapeutic innovations are expected as the etiology and pathogenesis are clarified.

A controlled randomized trial of budesonide versus prednisolone retention enemas in active distal ulcerative colitis

Sixty-four patients with active distal ulcerative colitis participated in a multicentre, randomized, investigator-blind trial to compare the effect of budesonide enema, 2 mg/100 ml, with prednisolone disodium phosphate enema, 31.25 mg/100 ml. Budesonide is a new potent corticosteroid with a rapid first-pass elimination. The patients were treated for 4 weeks, and the efficacy of the drugs were evaluated by sigmoidoscopy, histology, and subjective symptoms after 2 and 4 weeks. After 4 weeks of treatment 16 of 31 patients (52%) receiving budesonide enema had healed endoscopically, compared with 8 of 33 (24%) (p = 0.045) receiving prednisolone enema. Budesonide was superior to prednisolone in terms of both significantly improved sigmoidoscopic and histologic scores and subjective symptoms evaluated by visual analogue scales. The patients receiving prednisolone had a significant depression of endogenous cortisol levels during the treatment period, but not the patients receiving budesonide. Budesonide enema seems to be a promising therapy for active distal ulcerative colitis and causes no adverse reactions.

Treatment of distal ulcerative colitis with beclomethasone enemas: high therapeutic efficacy without endocrine side effects. A prospective, randomized, double-blind trial

Sixteen patients with 18 attacks of distal ulcerative colitis were treated randomly with either 0.5 mg topically administered beclomethasone dipropionate (BDP) or 5 mg betamethasone phosphate (BMT). The effect of the steroid enemas on adrenocortical function was examined by ACTH tests, which were performed before and 20 days after treatment. At completion of the trial, a marked suppression of the adrenocortical function was found in seven of eight patients treated for nine attacks with BMT but not in any patients in the BDP group (P less than 0.01). The mean posttreatment basal and stimulated plasma cortisol levels in the BMT group were significantly lower as compared with the BDP group. The overall therapeutic response assessed by score systems was comparable in the two treatment groups. It is concluded that, in the topical treatment of ulcerative colitis, BDP is preferable to BMT because it exerts an equal anti-inflammatory action without affecting adrenocortical function.

Comparative trial of sodium cromoglycate enemas with prednisolone enemas in the treatment of ulcerative colitis

A double blind multicentre study comparing sodium cromoglycate (600 mg/100 ml) by enema with prednisolone (20 mg/100 ml) by enema is reported. The study was conducted over a nine week period in the treatment of 70 patients with ulcerative colitis. Analysis of symptoms showed significant decreases in scores for patients in both groups, both at four and eight weeks; the only difference between the two groups was a significantly greater improvement in the reduction of rectal bleeding after four weeks in the prednisolone group. On sigmoidoscopy, both treatment groups showed a highly significant improvement after four and eight weeks with no significant differences being seen between the groups. Histology of the rectal biopsies showed a significant improvement in the inflammation of the mucosa for both treatment groups after four and eight weeks with no differences being observed between the groups. There were no significant changes in eosinophils from baseline and no difference between the groups at four and eight weeks.

Therapeutic benefits from a poorly absorbed prednisolone enema in distal colitis

A double blind controlled trial has been conducted in 40 patients to compare the therapeutic effects of prednisolone metasulphobenzoate enemas with those of prednisolone-21-phosphate enemas. Both enemas brought about improvement in symptoms and sigmoidoscopic appearances in more than 70% of patients treated. The absorption of prednisolone from the metasulphobenzoate enema in three patients was less than from the 21-phosphate enema. In view of the low plasma prednisolone concentrations obtained, there are theoretical advantages in using a poorly absorbed enema to avoid the possibility of systemic steroid effects in patients requiring long term steroid treatment.

Topical administration of 5-aminosalicylic acid enemas in patients with ulcerative colitis. Studies on rectal absorption and excretion

5-aminosalicylic acid (5-ASA) is a new treatment for patients suffering from ulcerative colitis but only limited information is available about its rectal absorption. We therefore studied seven patients with ulcerative colitis in remission, and five with active disease to determine acetylated and free 5-ASA plasma concentrations and urinary acetyl 5-ASA after the administration of three different types of enemas: (2 g 5-ASA/100 ml, 4 g/100 ml, and 200 ml). In patients in remission urinary acetyl 5-ASA excretion was dose and volume dependent (p less than 0.01; p less than 0.05) but this correlation was absent in active disease. Because aminosalicylates are usually eliminated through the kidney, these low values (10% in active disease and 19% in those in remission) suggest that the beneficial action may be local. Urinary recovery was significantly lower in patients with active disease (p less than 0.01; p less than 0.02). No accumulation of 5-ASA was found in plasma after repeated daily administration.

A comparison of prednisolone enemas with low-dose oral prednisolone in the treatment of acute distal ulcerative colitis

The therapeutic efficacy of prednisolone metasulphobenzoate enemas in the treatment of distal colitis has been compared with that of low-dose oral prednisolone, in a single-blind, cross-over trial. Treatment with steroid enemas resulted in symptomatic and sigmoidoscopic evidence of improvement more frequently than treatment with a dosage of oral steroid calculated to achieve similar plasma prednisolone levels. In addition to demonstrating, for the first time, that prednisolone metasulphobenzoate enemas are effective in the treatment of colitis, this study suggests that their efficacy is due to a local action rather than systemic absorption.

Drug therapy of inflammatory bowel disease

Although the etiology of inflammatory bowel disease is unknown and specific therapy is unavailable, enough information on existing empiric agents is available to allow rational therapy. These agents include sulfasalazine, steroids, immunosuppressive drugs, metronidazole and cholestyramine. Sulfasalazine is a two-part molecule that depends on bacterial cleavage in the colon to deliver locally acting 5-aminosalicylate, whose mechanism of action may relate to inhibition of prostaglandin synthesis. The other half of the molecule, sulfapyridine, is responsible for most of the side effects of the drug. While the efficacy of sulfasalazine in the treatment and prevention of attacks of ulcerative colitis is well established, its use in Crohn's disease appears to be limited to patients with active colitis and ileo-colitis. Sulfasalazine is of major benefit in preventing relapses in patients with ulcerative colitis in remission. New formulations of 5-aminosalicylate may allow delivery of the apparently active moiety to the small bowel and colon without concomitant sulfapyridine toxicity. Corticosteroids are highly effective in acute attacks of ulcerative colitis and Crohn's ileitis and ileo-colitis; the mechanism of antiinflammatory action remains speculative. However, maintenance therapy with steroids is ineffective in preventing relapses or recurrent attacks of either ulcerative colitis or Crohn's disease. Steroid enemas allow topical administration to patients with distal colitis and proctitis with few systemic side effects. In children with growth failure associated with active Crohn's disease, amelioration by steroid therapy may actually restore normal growth. Immunosuppressive agents such as azathioprine and 6-mercaptopurine are of little value in active Crohn's disease when administered alone; however, in combination with other agents they may help diminish steroid dose, close fistulae and prevent relapse. Their mode of action likely depends on long-term cytostatic effects on immune effector cells. Concern for leukopenia and the development of late malignancy has limited their use to patients not responding to other therapies. Metronidazole, an antimicrobial agent that is effective against anaerobes, has recently been shown useful in Crohn's disease involving the colon and perianal area. Its mechanism of action is uncertain, but may be related to its antibacterial actions on anaerobes. Cholestyramine can be successfully used to control bile salt-induced diarrhea in Crohn's patients with terminal ileal resections. Effective drug therapy of inflammatory bowel disease is only part of a total program of management including reassurance, frequent explanation, well-timed use of surgery, and an understanding physician.

Rectal drug administration: clinical pharmacokinetic considerations

The human rectum represents a body cavity in which drugs can be easily introduced and retained and from which absorption is well possible. There are important therapeutic reasons why it is sometimes preferable to give a drug rectally rather than orally, e.g. in cases of nausea and vomiting. Drawbacks of rectal drug administration include the interruption of absorption by defaecation and lack of patient acceptability. The mechanism of drug absorption from the rectum is probably no different to that in the upper part of the gastrointestinal tract, despite the fact that the physiological circumstances (e.g. pH, fluid content) differ substantially, Absorption from aqueous and alcoholic solutions may occur very rapidly, which has proved to be of considerable therapeutic value in the rapid suppression of acute convulsive attacks by diazepam (e.g. in children), but absorption from suppositories is generally slower and very much dependent on the nature of the suppository base, the use of surfactants or other additives, particle size of the active ingredient, etc. There is some evidence that hepatic first-pass elimination of high clearance drugs is partially avoided after rectal administration, e.g. lignocaine. This can be explained by the rectal venous blood supply: the upper part is connected with the portal system, whereas the lower part is directly connected with the systemic circulation. Plasma concentration data following rectal administration of representatives of several classes of drugs are reviewed: anticonvulsants, non-narcotic analgesics and non-steroidal anti-inflammatory agents, hypnosedatives and anaesthetics, strong analgesics, theophylline and derivatives, corticosteroids, antibacterial agents, thiazinamium, promethazine, hyoscine-N-butyl-bromide, streptokinase, progesterone, ergotamine tartrate and levodopa. Only limited number of cases has it been adequately shown that the rectal route of administration gives plasma concentrations which are comparable to the oral route. Potentially the rectal route offers the same possibilities as the oral route, but the influence of the formulation seems to be very critical. It is also likely that the future novel drug delivery systems with zero order release characteristics will be applied rectally. Interesting preliminary results have already been obtained with theophylline administered by 2ml osmotic pumps.