We hypothesis that the GSTM1/GSTT1 active variants with normal detoxification activity, could reduce the bioavailability of antihypertensive drugs and by doing so, GSTM1/GSTT1 deletion polymorphisms, in addition to their association with the risk of developing essential hypertension, could modulate the response to antihypertensive treatments, therefore the control of BP. The gene discussed is GSTM1; the disease is essential hypertension.