Before starting treatment, potential study participants received baseline tests, including a Doppler echocardiogram and a six-minute walk test to measure center and lung function. Seventy-four individuals who got a tricuspid regurgitant plane velocity in excess of or add up to 2.7 m/s and a six-minute walking distance of only 150-500 meters were contained in the study. The researchers then randomly assigned the scholarly research participants into two groups of 37 patients each. Half of the individuals were treated with sildenafil at escalating doses from 20, 40, and 80 mg three times each day, and the spouse received a placebo 3 x per day. In previous studies of patients with principal pulmonary hypertension, the highest dose of sildenafil experienced the greatest effect on blood circulation; however, to monitor for possible adverse effects associated with escalating doses, the sildenafil doses in this research were increased slowly, with dose increases made every four weeks.Fang, M.D., Vinay Shah, M.D., Richard B. Horenstein, M.D., Nita A. Limdi, Pharm.D., Ph.D., James A.S. Muldowney, III, M.D., Jaspal Gujral, M.B., B.S., Patrice Delafontaine, M.D., Robert J. Desnick, M.D., Ph.D., Thomas L. Ortel, M.D., Ph.D., Henny H. Billett, M.D., Robert C. Pendleton, M.D., Nancy L. Geller, Ph.D., Jonathan L. Halperin, M.D., Samuel Z. Goldhaber, M.D., Michael D. Caldwell, M.D., Ph.D., Robert M. Califf, M.D., and Jonas H. Ellenberg, Ph.D. For the COAG Investigators: A Pharmacogenetic versus a Clinical Algorithm for Warfarin Dosing The necessity for clinical trials before widespread adoption of genotype-guided drug dosing and selection remains widely debated.1-4 Warfarin therapy has served as a model for the prospect of pharmacogenetics to improve patient care.1 Observational studies have identified two genes, CYP2C9 and VKORC1, that are connected with variation in warfarin maintenance doses.