Shaman Pharmaceuticals Inc. _ which in May 1995postponed Phase II trials of Provir for respiratorysyncytial virus (RSV) because the oral drug wasn't beingabsorbed by patients _ turned a setback into anadvantage by targeting a new indication for the leadcompound.
Lisa Conte, president and CEO of South San Francisco-based Shaman, said Provir, derived from an extract of themedicinal croton plant in Latin American, will be testedas a treatment for secretory, or watery diarrhea. Safetyand pharmacokinetics data from the Phase I RSV trial canbe applied to evaluation of Provir as an anti-diarrhealagent, she added, meaning Phase II trials will not bedelayed. Results are expected in the first half of next year,which puts the drug development back on its originaltimetable.
The croton plant, Conte said, is a medicinal herb withtraditional uses in Latin America including treatments forrespiratory diseases and gastrointestinal disorders. Theherb still is sold throughout the continent.
Shaman uses what it describes as an ethnobotanicalapproach to drug discovery. The company screenstropical plants from Africa, Southeast Asia and LatinAmerican for their active ingredients.
Although Phase I studies showed Provir was safe whenadministered to children with RSV, the oral drug was notadequately absorbed. However in treatment of diarrhea,Conte said, low absorption is a benefit. Preclinical studiesshowed Provir inhibits secretion of chloride ions bystomach and intestinal cells. Oversecretion of chloride,spurred by pathogenic bacteria, causes an abnormalbuildup of fluid, resulting in diarrhea and eventualdehydration.
Provir, Conte said, is targeted for treatment of diarrhea,including traveler's diarrhea, caused by bacteria, such asEscherichia coli and the microbe responsible for cholera.More than 16 million people worldwide are diagnosedwith infectious diarrhea each year, she added.
The Phase II trials for Provir will be challenge studies inwhich healthy volunteers will be given the cholera toxinin a hospital setting to induce watery diarrhea. Provir thenwill be administered to determine if it can halt theproblem.
Shaman's stock (NASDAQ:SHMN) closed Tuesday at$5.50, up 12 cents. n
-- Charles Craig
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