Co-Diovan

Valsartan is an oral medicine that belongs to a class called angiotensin receptor blockers (ARBs). It is orally active and works as a specific angiotensin II antagonist at the AT1 subtype. When angiotensin attaches to its receptors, the blood vessels narrow (vasoconstrict) and blood pressure goes up (hypertension). Valsartan blocks the angiotensin II receptor, so the vessels dilate and blood pressure falls, without any change in pulse rate. Its affinity for the AT1 receptor is much greater than for the AT2 receptor (about 20,000-fold). It does not bind or block other hormone receptors or ion channels known to be important in cardiovascular regulation. Hydrochlorothiazide is a thiazide diuretic. Thiazides act on the renal tubular mechanisms of electrolyte reabsorption and directly increase the excretion of sodium and chloride in approximately equivalent amounts. The indirect effect comes from the diuretic action of hydrochlorothiazide, which reduces plasma volume. That brings increases in plasma renin activity, aldosterone secretion and urinary potassium loss, and a decrease in serum potassium. Angiotensin II mediates the renin-aldosterone link, so giving an angiotensin converting enzyme (ACE) inhibitor together with the diuretic tends to reverse the potassium loss these diuretics cause.

Pregnancy: Valsartan should not be used during pregnancy, because in the 2nd and 3rd trimester it can injure the fetus and even cause its death. If pregnancy is detected, Valsartan should be stopped as soon as possible.

Nursing mothers: It is not known whether Valsartan passes into human milk. Hydrochlorothiazide does pass into breast milk.

Patients with renal impairment can follow the usual regimens of Valsartan + Hydrochlorothiazide as long as their creatinine clearance is above 30 ml/min. If the renal impairment is more severe, loop diuretics are preferred to thiazides, so hydrochlorothiazide is not recommended in that case.

Patients with hepatic impairment need care when taking Valsartan + Hydrochlorothiazide.

Valsartan: There isn't much data on overdose in humans. The most likely effects are low blood pressure (hypotension) and a fast heart rate (tachycardia). A slow heart rate (bradycardia) could also occur, because of parasympathetic (vagal) stimulation. If the blood pressure falls too far, the patient should lie flat on their back, and if needed, normal saline should be given by intravenous infusion.

Hydrochlorothiazide: The signs and symptoms seen most often come from electrolyte depletion (hypokalemia, hypochloremia and dehydration), which results from excessive diuresis. If digitalis has been given along with it, hypokalemia may make cardiac arrhythmias worse. It has not been established how much Hydrochlorothiazide hemodialysis removes.