Complex sentence: He played the leading role in developing a rational pharmaceutical policy which ensured that the poor people would get good quality drugs at the lowest possible price to the country and that doctors would prescribe the minimum required drugs to treat the patient's illness.
Split into simpler sentences: He played the leading role in developing a rational pharmaceutical policy aimed at ensuring that impoverished people would get reasonable drugs at a low price. Further, the programs are aimed towards ensuring that doctors prescribe the minimum required drugs to treat the patient's illness.