Charak Samhita
सम्प्रधार्य बलं तस्मादामयस्यौषधस्य च । नैवातिबहु नात्यल्पं भैषज्यमवचारयेत् ॥३१४॥
Similarly excess water in field damages crop, the same way excess of medicine damages health of a person. Hence medicine should be given as per the status of disease; neither should it be given in very higher dose nor in very smaller doses to treat disease.
english translation
sampradhArya balaM tasmAdAmayasyauSadhasya ca । naivAtibahu nAtyalpaM bhaiSajyamavacArayet ॥314॥
hk transliteration by Sanscript