[Bioavailability of sotalol in short bowel syndrome]

Drug absorption from oral formulations in patients with short bowel syndrome: a comprehensive update of the literature

INTRODUCTION

Drug absorption is often altered and typically diminished in patients with short bowel syndrome (SBS). It is important to understand the patient's gastrointestinal anatomy, the absorptive capacity of the remaining bowel, and the physicochemical and pharmacokinetic properties of the drug to optimize oral pharmacotherapy.

AREAS COVERED

The primary focus was to provide an updated understanding of the absorption of various drugs in patients with short bowel syndrome. Forty-seven studies covering 13 different drug classes were included in the review and study details, patient characteristics, drug characteristics and pharmacokinetic findings were summarized for each drug class.

EXPERT OPINION

Improving and simplifying drug treatment in patients with SBS have high priority, but the patients are multi diseased so knowledge regarding absorption of drugs as e.g. antithrombotic agents, immunosuppressants is urgently needed. Therefore, it is crucial to advance our understanding of the fundamental factors involved in drug absorption, spanning from drug design to pathophysiology. With the growing knowledge in drug design and gastrointestinal pathophysiology, we anticipate the development of computer models that can accurately predict optimal absorption in the future.

The impact of intestinal failure on oral drug absorption: a review

INTRODUCTION

Intestinal failure is a complex gastroenterological condition that occurs as a result of reduced intestinal absorption of nutrients and/or water and electrolytes. Without treatment, nutritional depletion and/or dehydration will result. It can be acute or chronic and occurs secondary to a variety of causes, including massive bowel resection, inflammatory bowel diseases of the bowel, and small bowel dysfunction.

RESULTS AND DISCUSSION

Resection of the small bowel results in a range of physiological changes that affect the absorption of nutrients, water, and electrolytes. In addition, these changes may also affect the absorption of orally administered medication. However, there is only minimal published literature regarding this, with the publications limited to case reports of failure or efficacy of certain medicines such as digoxin and warfarin in individual patients. Due to the highly heterogeneous nature of intestinal failure patients, there is little generalizability of the information within these articles to other patients. Only one article seeks to provide limited practical advice regarding prescribing in this complex patient group.

CONCLUSION

The input of specialist pharmacists is necessary in the management of these patients to ensure that appropriate drugs and formulations are prescribed in a timely manner to optimize absorption and resultant efficacy.

Enteral Drug Absorption in Patients with Short Small Bowel

Drug therapy may become difficult when a significant amount of the small intestine is resected, as happens in patients with a short small bowel. Drug absorption from the gastrointestinal tract is altered in these patients; however, this effect is variable in patients and differs with each drug. Literature regarding clinical outcomes of normal or alternative administration routes in patients with a short small bowel is limited. We explored what is written about the normal absorption of commonly used drugs and what difference the resection of different but substantial parts of the small intestine makes. Changes in the gastrointestinal tract after resection of >50% of the small intestine causes malabsorption of macronutrients and micronutrients, and may alter the drug absorption process. The metabolic activity of the abundantly present intestinal lactobacilli can also affect the enteral drug absorption in patients with short small bowel as this results in the production of lactic acid, gaseous CO(2), ethanol and an increased bile acid deconjugation. Accelerated intestinal luminal transit time causes a reduction in absorption of certain antimicrobial agents, digoxin, hydrochlorothiazide, ciclosporin, cimetidine, mesalazine (5-aminosalicylic acid), oral contraceptives and levothyroxine. Gastric hypersecretion and lack of sufficient contact time with the intestinal mucosa in patients with short small bowel leads to insufficient absorption of drugs such as omeprazole. Successful treatment with warfarin, tricyclic antidepressants, metronidazole, fluconazole, procainamide, sotalol and pindolol are reported in several studies. Many different factors cause this variability in drug absorption in such patients. Monitoring the serum drug concentration in these patients may ease dealing with the management problems.