anti-estrogen drug pathway tamoxifen drug pathway 2011-01-17T01:05:40Z PW:0000837 The pharmacokinetics and pharmacodynamics pathway of tamoxifen - one of the most widely used anti-estrogen drug that targets the estrogen receptor. The drug is a modulator than acts as an antagonist in breast cancer cells but can be an agonist in bone and the cardiovascular system. Genetic variations can result in changes in drug availability and can cause differences in the response of the organism to the drug. pathway vpetri