InKine Pharmaceutical Co. Inc. is beginning a Phase III study of its next-generation sodium phosphate purgative tablet, INKP-102, after agreeing with the FDA on a special protocol assessment.

Patient enrollment got under way to test two dosing regimens - 32 and 40 tablets of INKP-102 - against InKine's currently marketed Visicol product at the labeled dose of 40 tablets in adults scheduled for colonoscopy. Launched in January 2001, Visicol is the only tablet purgative preparation indicated for bowel cleansing prior to colonoscopy.

The Blue Bell, Pa.-based specialty pharma company hopes to have the second such product on the market. Though both INKP-102 and Visicol have the same active ingredient, InKine expects the testing to show that it has built a better mousetrap.

"We want to produce a product that gastroenterologists will find more acceptable with respect to the amount of residue in the colon," Martin Rose, InKine's executive vice president for research and development, told BioWorld Today. "The [Visicol] tablet sometimes leaves a fluffy white residue, and it may take a minute or two to wash or suction."

The substance, microcrystalline cellulose, is an inert but highly insoluble substance used to bind the Visicol tablets. INKP-102 tablets do not contain microcrystalline cellulose.

"We have been working to replace that tablet binder with a soluble binder," Rose added, "and we have."

Also, INKP-102 tablets are smaller than Visicol tablets and both INKP-102 dosing regimens follow a more convenient dosing schedule than Visicol.

The multicenter, investigator-blinded study will examine the safety, efficacy and patient acceptance of the new product. Three arms with 255 patients apiece will receive either of the two INKP-102 doses or Visicol. The trial's primary endpoint is to prove INKP-102's non-inferiority to Visicol in terms of overall colon cleansing.

The company said the FDA indicated that the Phase III study, together with a recently completed Phase II study, could support INKP-102's approval. The Phase II findings showed that both dosing regimens were well tolerated and proved positive in cleansing the colon. Phase III data are expected to be available in the first half of next year.

"The special protocol assessment says that if you follow this protocol, hit your endpoint, and everything looks good in terms of clinical data, it ought to be OK," Rose said. "The NDA filing, we think, will be in 2005."

Should the product receive approval, he added that InKine would market it through its internal sales force that already details Visicol. That product generated about $4.8 million in second-quarter sales, and the company expects it to produce between $20 million and $22 million for the full fiscal year.

Though INKP-102 would eat into Visicol's share of colonoscopy-related bowel-cleansing sales, the company plans to keep the product around. It is testing Visicol for use as a laxative in treating patients with constipation, and expects to begin a Phase III study in that indication next year.

InKine sells another product, IB-Stat, an oral hyoscyamine spray primarily used to treat irritable bowel syndrome. The company also promotes an outside product, VSL#3, a probiotic for gastrointestinal health.

InKine is conducting a Phase IIb trial of a Crohn's disease product called Colirest, and also plans to test the use of sodium phosphate for colon cleansing in surgery patients.

On Thursday, the company's stock (NASDAQ:INKP) lost 4 cents to close at $4.81.