the compounds of formula i can be readily prepared by one of ordinary skill in the art . suitable synthetic methods are found , for example , in u . s . pat . nos . 4 , 766 , 114 , 3 , 758 , 528 and 3 , 821 , 249 , all of malen et al ., and u . s . pat . no . 6 , 441 , 165 of blanchard et al ., the entire disclosures of which are herein incorporated by reference . certain compounds of formula i , such as tianeptine ( see formula ii , below ), possess an asymmetric carbon . the position of the asymmetric carbon is denoted by an asterisk (*) in formula i ; for this carbon to be considered asymmetric , each of the four groups attached to it must be nonequivalent . one skilled in the art can readily determine which compounds of formula i possess an asymmetric carbon . those compounds of formula i which have this asymmetric carbon can exist as both ( r ) and ( s ) enantiomers . typically , the ( r ) and ( s ) enantiomers of a given compound of formula i exist as a racemate . in the practice of the present invention , both racemates and individual ( r ) or ( s ) enantiomers of a compound of formula i can be used to treat ibs or nud . according to certain embodiments of the invention , an ( r )- enantiomer of a compound of formula i which is substantially free of the corresponding ( s )- enantiomer , or an ( s )- enantiomer of a compound of formula i which is substantially free of the corresponding ( r )- enantiomer , is used to treat ibs or nud . to isolate the individual ( r )- and ( s )- enantiomers of a compound of formula i , the racemate of that compound must be resolved . this resolution can be achieved by converting a racemic compound of formula i into a pair of diastereomers , for example by covalently bonding to an optically active moiety or by salt formation with an optically active base or acid . either method provides a molecule with a second chiral center , thus generating a pair of diastereomers . the diastereomeric pair can then be separated by conventional methods , such as crystallization or chromatography . for example , racemic compounds of formula i can be converted to the ( s )- dibenzoyltartaric acid salt , which is a diastereomeric mixture of ss and rs configurations . the pairs of diastereomers ( r , s ) and ( s , s ) possess different properties ( e . g ., differential solubilities ) that allow for the use of conventional separation methods . fractional crystallization of diastereomeric salts from a suitable solvent is one such separation method . racemic compounds of formula i can be separated into enantiomers without diastereomer formation , for example , by differential absorption on a chiral stationary phase of a chromatography ( e . g ., hplc ) column . preparative hplc columns suitable for diastereomer separation are commercially available with a variety of packing materials to suit a broad range of separation applications . stationary phases suitable for resolving racemic compounds of formula i include : ( i ) macrocyclic glycopeptides , such as silica - bonded vancomycin which contains 18 chiral centers surrounding three pockets or cavities ; chiral α 1 - acid glycoprotein is a highly stable protein immobilized onto spherical silica particles that tolerates high concentrations of organic solvents , high and low ph , and high temperatures . human serum albumin is especially suited for the resolution of weak and strong acids and zwitterionic and nonprotolytic compounds , but is also used to resolve basic compounds . cbh is a very stable enzyme that that is typically immobilized onto spherical silica particles for separating enantiomers of basic drugs from many compound classes . other chromatographic techniques suitable for resolving racemic compounds of formula i include chiral chromatography using macrocyclic glycopeptide as a stationary phase on a chirobiotic v ™ column ( asteac , whippany , n . j .) as described in u . s . pat . no . 6 , 080 , 736 , the entire disclosure of which is herein incorporated by reference , and chiral chromatography using a chiral α 1 - acid glycoprotein as a stationary phase on a chiral - agp ™ column ( chromtech , cheshire , uk ), as described in fitos et al ., j chromatogr ., 1995 , 709 : 265 , the entire disclosure of which is herein incorporated by reference . a preferred compound of formula i for use in the present methods is tianeptine , or a pharmaceutically acceptable salt thereof . the structure of tianeptine is given in formula ii : the bond designated by indicates that the absolute conformation about the asymmetric carbon can be either ( r ) or ( s ). tianeptine can be readily obtained by one of ordinary skill in the art , for example by the synthetic techniques described above . tianeptine is also sold commercially as stablon ®. the ( r ) or ( s ) enantiomers of tianeptine can be isolated , for example , by the techniques discussed above . thus , in preferred embodiments of the present invention , the ( r )- enantiomer of tianeptine which is substantially free of the corresponding ( s )- enantiomer , or the ( s )- enantiomer of tianeptine which is substantially free of the corresponding ( r )- enantiomer , is used in the present methods . in the practice of the invention , the compounds of formula i described above can take the form of a pharmaceutically - acceptable salt . the term “ salts ”, embraces salts commonly used to form alkali metal salts and to form addition salts of free acids or free bases . for example , pharmaceutically - acceptable acid addition salts may be prepared from an inorganic acid or from an organic acid . suitable inorganic acids include hydrochloric , hydrobromic , hydroiodic , nitric , carbonic , sulfuric and phosphoric acid . suitable organic acids include aliphatic , cycloaliphatic , aromatic , araliphatic , heterocyclic , carboxylic and sulfonic classes of organic acids , such as formic , acetic , propionic , succinic , glycolic , gluconic , lactic , malic , tartaric , citric , ascorbic , glucuronic , maleic , fumaric , pyruvic , aspartic , glutamic , benzoic , anthranilic , mesylic , salicylic , 4 - hydroxybenzoic , phenylacetic , mandelic , embonic ( pamoic ), methanesulfonic , ethanesulfonic , benzenesulfonic , pantothenic , 2 - hydroxyethanesulfonic , toluenesulfonic , sulfanilic , cyclohexylaminosulfonic , stearic , algenic , beta - hydroxybutyric , galactaric and galacturonic acid . suitable pharmaceutically acceptable base addition salts of the compounds of formula i , include metallic salts made from calcium , magnesium , potassium , sodium and zinc , or organic salts made from n , n ′- dibenzylethylenediamine , chloroprocaine , choline , diethanolamine , ethylenediamine , meglumine ( n - methylglucamine ) and procaine . all of these salts can be prepared by conventional means from the corresponding compound of formula i by reacting , for example , the appropriate acid or base with the compound of formula i . the compounds of formula i , in particular tianeptine , can be used to treat ibs or nud in a subject who has been diagnosed with either disorder . as used herein , a “ subject ” is includes humans and non - human mammals . non - human mammals include bovines , ovines , porcines , equines , canines , felines , and rodents ( e . g ., rat , mouse , guinea pig and rabbit ). preferably , the subject is a human . diagnosis of ibs is within the skill in the art . for example , ibs can be diagnosed on the basis of the modified “ rome criteria .” the modified rome criteria are ( a ) the presence for at least 12 weeks ( not necessarily consecutive ) in the preceding 12 months of abdominal discomfort or pain that cannot be explained by structural or biochemical abnormalities ; and ( b ) at least two of the following three symptoms : ( i ) pain relieved with defecation ; ( 2 ) pain , when the onset thereof is associated with a change in the frequency of bowel movements ( diarrhea or constipation ); and pain when the onset thereof is associated with a change in the form of the stool ( lose , watery , or pellet - like ). the diagnosis of nud is also within the skill in the art . for example , criteria for diagnosing nud include the presence of chronic or recurrent upper abdominal pain or discomfort for a period of more than three months &# 39 ; duration , which has no apparent organic cause . these symptoms must be present for more than 25 percent of the time . bloating , nausea , early satiety , eructation and heartburn may also be present . see , e . g ., fisher rs , parkman hp , new engl j med 1998 ; 339 : 1376 - 1381 and locke gr , mayo clin proc 1999 ; 74 : 1011 - 15 , the entire disclosures of which are herein incorporated by reference . nud can be differentiated from ibs by determining whether the abdominal pain reported by the subject is associated with abnormal bowel habits . if such an association is present , the condition is considered to be ibs rather than nud . see freidman ls , new engl j med 1998 ; 339 : 1928 - 30 , the entire disclosure of which is herein incorporated by reference . in the practice of the invention , ibs or nud are treated by administering an effective amount of at least one compound of formula i to a subject in need of such treatment , such that the symptoms of ibs or nud are reduced . as used herein , an “ effective amount ” of a compound of formula i used to treat ibs refers to the amount of the compound that prevents or alleviates one or more symptoms of ibs . a physician can readily determine when symptoms of ibs are prevented or alleviated , for example through clinical observation of a subject , or through reporting of symptoms by the subject during the course of treatment . likewise , an “ effective amount ” of a compound of formula i used to treat nud refers to the amount of the compound that prevents or alleviates the symptoms of nud . again , a physician can readily determine when symptoms of nud are prevented or alleviated through clinical observation of a subject or through reporting of symptoms by the subject during the course of treatment . one skilled in the art can readily determine an effective amount of a compound of formula i to be administered , by taking into account factors such as the size , weight , age and sex of the subject , the extent of disease penetration or persistence and severity of symptoms , and the route of administration . generally , an effective amount of the compounds of formula i administered to a subject is from about 2 to about 100 mg / kg / day , preferably from about 5 to about 60 mg / kg / day , and more preferably about 30 mg / kg / day . higher or lower doses are also contemplated . the compounds of formula i can be administered to a subject by any route , for example by enteral ( e . g ., oral , rectal , intranasal , etc .) and parenteral administration . parenteral administration includes , for example , intravenous , intramuscular , intraarterial , intraperitoneal , intravaginal , intravesical ( e . g ., into the bladder ), intradermal , topical or subcutaneous administration . also contemplated within the scope of the invention is the instillation of the compounds of formula i into the body of the subject , for example in a controlled release formulation , with systemic or local release of the compound to occur over time or at a later time . preferably , the compound of formula i is localized in a depot for controlled release to the circulation or to a local site such as the gastrointestinal tract . in the practice of the present methods , compounds of formula i can be administered in the form of a pharmaceutical composition comprising at least one compound of formula i and a pharmaceutically acceptable carrier . pharmaceutical formulations of the invention can comprise from 0 . 1 to 99 . 99 weight percent of at least one compound of formula i . the pharmaceutical compositions of the invention can be formulated according to standard practices in the field of pharmaceutical preparations . see alphonso gennaro , ed ., remington &# 39 ; s pharmaceutical sciences . 18th ed ., ( 1990 ) mack publishing co ., easton , pa . suitable dosage forms can comprise , for example , tablets , capsules , solutions , parenteral solutions , troches , suppositories , or suspensions . by “ pharmaceutically acceptable carrier ” is meant any diluent or excipient that is compatible with the other ingredients of the formulation , and which is not deleterious to the recipient . the pharmaceutically acceptable carrier can be selected on the basis of the desired route of administration , in accordance with standard pharmaceutical practices . pharmaceutical compositions of the invention for parenteral administration can take the form of an aqueous or nonaqueous solution , dispersion , suspension or emulsion . in preparing pharmaceutical compositions of the invention for parenteral administration , at least one compound of formula i can be mixed with a suitable pharmaceutically acceptable carrier such as water , oil ( particularly a vegetable oil ), ethanol , saline solutions ( e . g ., normal saline ), aqueous dextrose ( glucose ) and related sugar solutions , glycerol , or glycols such as propylene glycol or polyethylene glycol . pharmaceutical compositions of the invention for parenteral administration preferably contain a water - soluble salt of at least one compound of formula i . stabilizing agents , antioxidizing agents and preservatives can also be added to the pharmaceutical compositions for parenteral administration . suitable antioxidizing agents include sulfite , ascorbic acid , citric acid and its salts , and sodium edta . suitable preservatives include benzalkonium chloride , methyl - or propyl - paraben , and chlorbutanol . in preparing pharmaceutical compositions of the invention for oral administration , at least one compound of formula i can be combined with one or more solid or liquid inactive ingredients to form tablets , capsules , pills , powders , granules or other suitable oral dosage forms . for example , at least one compound of formula i can be combined with at least one pharmaceutically acceptable carrier such as a solvent , filler , binder , humectant , disintegrating agent , solution retarder , absorption accelerator , wetting agent absorbent or lubricating agent . in one embodiment , at least one compound of formula i is combined with carboxymethylcellulose calcium , magnesium stearate , mannitol and starch , and is formed into tablets by conventional tableting methods . in a preferred embodiment , tianeptine is formulated into a tablet comprising cellulose and a calcium salt , as described in u . s . pat . no . 5 , 888 , 542 , the entire disclosure of which is herein incorporated by reference . pharmaceutical compositions of the invention can also be formulated so as to provide controlled - release of at least one compound of formula i upon administration of the composition to a subject . preferably , a controlled - release pharmaceutical composition of the invention is capable of releasing at least one compound of formula i into a subject at a desired rate , so as to maintain a substantially constant pharmacological activity for a given period of time . formulation of controlled - release pharmaceutical compositions of the invention is within the skill in the art . controlled release formulations suitable for use in the present invention are described in , for example , u . s . pat . no . 5 , 674 , 533 ( liquid dosage forms ), u . s . pat . no . 5 , 059 , 595 ( gastro - resistant tablet ), u . s . pat . no . 5 , 591 , 767 ( liquid reservoir transdermal patch ), u . s . pat . no . 5 , 120 , 548 ( device comprising swellable polymers ), u . s . pat . no . 5 , 073 , 543 ( ganglioside - liposome vehicle ), u . s . pat . no . 5 , 639 , 476 ( stable solid formulation coated with a hydrophobic acrylic polymer ), the entire disclosures of which are herein incorporated by reference . biodegradable microparticles can also be used to formulate controlled - release pharmaceutical compositions suitable for use in the present invention , for example as described in u . s . pat . nos . 5 , 354 , 566 and 5 , 733 , 566 , the entire disclosures of which are herein incorporated by reference . in one embodiment , controlled - release pharmaceutical compositions of the invention comprise at least one compound of formula i and a controlled - release component . as used herein , a “ controlled - release component ” is a compound such as a polymer , polymer matrix , gel , permeable membrane , liposome and / or microsphere that induces the controlled - release of the compound of formula i into the subject upon exposure to a certain physiological compound or condition . for example , the controlled - release component can be biodegradable , activated by exposure to a certain ph or temperature , by exposure to an aqueous environment , or by exposure to enzymes . an example of a controlled - release component which is activated by exposure to a certain temperature is a sol - gel . in this embodiment , at least one compound of formula i is incorporated into a sol - gel matrix that is a solid at room temperature . this sol - gel matrix is implanted into a subject having a body temperature high enough to induce gel formation of the sol - gel matrix , thereby releasing the active ingredient into the subject . the practice of the invention is illustrated by the following non - limiting example . the model used in the present study is predictive of agents that can be used to treat the alterations in propulsion of intestinal contents that occur in ibs . the model is sensitive to test compounds which produce inhibitory effects on propulsive motor activity , but is not sensitive to test compounds which increase colonic propulsive motility . the model thus provides a direct measure of colonic propulsion by measuring movement of a glass bead through the mouse colon . test compounds that slow the rate at which the glass bead is expelled are predicted to have utility in the treatment of ibs . the model used in the present study can also evaluate test compounds that may cause constipation , have antidiarrheal activity , or have selective visceral anti - nociceptive activity . thus , the model is useful for evaluating test compounds for treating nud as well as ibs . for the present study , 48 female , 6 week old swiss webster mice ( 18 - 30 g ) were divided into the following test groups : three treatment groups receiving , respectively , 10 mg / kg tianeptine ( n = 9 ), 30 mg / kg tianeptine ( n = 10 ), and 60 mg / kg tianeptine ( n = 9 ); a control group receiving 10 mg / kg of the antidiarrheal loperamide ( n = 9 ); and a control group receiving vehicle only ( n = 10 ). each animal was dosed orally with either tianeptine , loperamide or vehicle , as appropriate . thirty minutes after dosing , a 3 mm glass bead was inserted through the anus of each animal into the distal colon to a depth of 2 cm , using a glass rod . the animals were observed for expulsion of the bead , and the time of expulsion was noted . any animal that had not expelled the bead within a cut - off time of 60 minutes after bead insertion was sacrificed , and the position of the bead in the lumen of the colon was verified . mean and standard error of the mean were calculated for the expulsion times for each group . the data are summarized in table 1 below . the animals were also observed for signs of gross toxicity and / or behavioral changes during the 60 - 90 minute interval after dosing . such observations included gross evaluation of skin and fur , eyes and mucous membranes , respiratory , circulatory , autonomic and central nervous system , somatomotor activity and behavioral patterns . particular attention was directed to observation of tremors , convulsions , salivation , diarrhea , sleep and coma no signs of gross toxicity or behavioral changes were observed . these data show that tianeptine produces a dose - related inhibition of colonic propulsion . the 30 mg / kg tianeptine dose was equivalent in effect to a 10 mg / kg dose of loperamide . thus , compounds of formula i , in particular tianeptine , are useful in the treatment of ibs and nud . all references cited herein are incorporated by reference . the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and , accordingly , reference should be made to the appended claims , rather than to the foregoing specification , as indication the scope of the invention .
compounds according to the formula as defined herein are administered for the treatment of irritable bowel syndrome and nonulcer dyspepsia .