Methods of preventing and treating gastrointestinal dysfunction

#The present invention generally relates to methods of preventing and treating gastrointestinal (GI) dysfunction. More specifically, the present invention relates to methods of preventing and treating gastrointestinal dysfunction, particularly postoperative ileus and post-partum ileus, in a patient undergoing surgery or other biological stress, by administering 4-aryl-piperidine derivatives.

#It is well known that opioid drugs target three types of endogenous opioid receptors (i.e., μ, δ, κ receptors) in biological systems. Many opiates, such as morphine, are mu opioid agonists that are often used as analgesics for the treatment of severe pain due to their activation of mu opioid receptors in the brain and central nervous system (CNS). Opioid receptors are, however, not limited to the CNS, and may be found in other tissues throughout the body. A number of side effects of opioid drugs may be caused by activation of these peripheral receptors. For example, administration of mu opioid agonists often results in intestinal dysfunction due to the large number of receptors in the wall of the gut (Wittert, G., Hope, P. and Pyle, D., Biochemical and Biophysical Research Communications, 1996, 218, 877-881; Bagnol, D., Mansour, A., Akil, A. and Watson, S. J., Neuroscience, 1997, 81, 579-591). Specifically, opioids are generally known to cause nausea and vomiting as well as inhibition of normal propulsive gastrointestinal function in animals and man (Reisine, T., and Pasternak, G., Goodman & Gilman's The Pharmacological Basis of Therapeutics Ninth Edition, 1996, 521-555) resulting in side effects such as, for example, constipation.

#Recent evidence has indicated that naturally occurring endogenous opioid compounds may also affect propulsive activity in the gastrointestinal (GI) tract. Met-enkephalin, which activates mu and delta receptors in both the brain and gut, is one of several neuropeptides found in the GI tract (Koch, T. R., Carney, J. A., Go, V. L., and Szurszewski, J. H., Digestive Diseases and Sciences, 1991, 36, 712-728). Additionally, receptor knockout techniques have shown that mice lacking mu opioid receptors may have faster GI transit times than wild-type mice, suggesting that endogenous opioid peptides may tonically inhibit GI transit in normal mice (Schuller, A. G. P., King, M., Sherwood, A. C., Pintar, J. E., and Pasternak, G. W., Society of Neuroscience Abstracts, 1998, 24, 524). Studies have shown that opioid peptides and receptors located throughout the GI tract may be involved in normal regulation of intestinal motility and mucosal transport of fluids in both animals and man (Reisine, T., and Pasternak, G., Goodman & Gilman's The Pharmacological Basis of Therapeutics Ninth Edition, 1996, 521-555). Other studies show that the sympathetic nervous system may be associated with endogenous opioids and control of intestinal motility (Bagnol, D., Herbrecht, F., Jule, Y., Jarry, T., and Cupo, A., Regul. Pept., 1993, 47, 259-273). The presence of endogenous opioid compounds associated with the GI tract suggests that an abnormal physiological level of these compounds may lead to bowel dysfunction.

#FIG. 1 shows the free plasma concentration of alvimopan (12 mg dose) as a function of time.

#FIG. 2 shows GI score as a function of log of plasma concentrations measured as AUC (τ) (in ng-ml/hr) with a GI score measured by radio-opaque markers in subjects given loperamide with either placebo or one of three doses of I.V. alvimopan (0.1 mg b.i.d, 0.45 mg b.i.d., and 1 mg b.i.d.) selected to target different plasma concentrations (4.5, 20, and 45 ng/ml, respectively).

#The methods of the present invention are directed to treating and preventing gastrointestinal dysfunction, particularly postoperative ileus and post-partum ileus, in a patient undergoing surgery. Different types of ileus may be treated and/or prevented using the methods of the present invention. The present methods are particularly suitable for treating and/or preventing postoperative ileus and post-partum ileus. “Postoperative ileus,” which may follow surgery such as laparotomy, may be characterized by such symptoms as, for example, obstruction of the gut, particularly in the colon, resulting in nausea, vomiting, lack of passage of flatus and/or stools, abdominal distention and lack of bowel sounds. This condition generally lasts from about 3 to about 5 days, but may endure longer, including up to about one week. Longer durations are generally characteristic of a more severe form of ileus, termed post-surgical paralytic ileus, which may affect other portions of the GI tract in addition to the colon. “Post-partum ileus” generally refers to obstruction of the gut, particularly the colon, following parturition. Both natural and surgically-assisted procedures during parturition may lead to post-partum ileus treated by the present invention. Symptoms of post-partum ileus and postoperative ileus are similar.

#As employed above and throughout the disclosure, the following terms, unless otherwise indicated, shall be understood to have the following meanings.

#As used herein, “alkyl” refers to an optionally substituted, saturated straight, branched, or cyclic hydrocarbon having from about 1 to about 20 carbon atoms (and all combinations and subcombinations of ranges and specific numbers of carbon atoms therein), with from about 1 to about 8 carbon atoms, herein referred to as “lower alkyl”, being preferred. “Branched” refers to an alkyl group in which a lower alkyl group, such as methyl, ethyl, or propyl, is attached to a linear alkyl chain. In certain preferred embodiments, the alkyl group is a C1-C5 alkyl group, i.e., a branched or linear alkyl group having from 1 to about 5 carbons. In other preferred embodiments, the alkyl group is a C1-C3 alkyl group, i.e., a branched or linear alkyl group having from 1 to about 3 carbons. Exemplary alkyl groups include methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl. “Lower alkyl” refers to an alkyl group having 1 to about 6 carbon atoms. Preferred alkyl groups include the lower alkyl groups of 1 to about 3 carbons. Alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, cyclopentyl, isopentyl, neopentyl, n-hexyl, isohexyl, cyclohexyl, cyclooctyl, adamantyl, 3-methylpentyl, 2,2-dimethylbutyl, and 2,3-dimethylbutyl.