Pharmacology
Valsartan is an oral medication that
belongs to a class of medications called angiotensin receptor blockers (ARBs).
It is a specific angiotensin II antagonist with oral activity, which acts on
the AT1 subtype. Binding of angiotensin to its receptors causes the blood
vessels to narrow (vasoconstriction), which leads to an increase in blood
pressure (hypertension). Valsartan blocks angiotensin II receptors. By blocking
the effects of angiotensin, valsartan can dilate blood vessels and lower blood
pressure without affecting the pulse rate. The affinity of valsartan for the
AT1 receptor is much higher than that for the AT2 receptor (about 20,000
times). It does not bind to or block other hormone receptors or ion channels
that are known to be important for cardiovascular regulation.
Dosage & Administration
Hypertension: The usual dose of Valsartan is 80 to 160 mg once daily. The maximum
dose is 320 mg daily. Maximum blood pressure reduction occurs within 4
weeks.
Heart failure: The usual dose is 40 mg twice daily and may be
increased to 80-160 mg twice daily.
Post-Myocardial Infarction: The initial dose after myocardial
infarction is 20 mg twice daily. The dose should be increased with a target of
160 mg daily if tolerated without side effects.
Administration of Valsartan with food
decreases the absorption of Valsartan by about 40%, so it should be taken on an
empty stomach. No initial dosage adjustment is required for elderly patients
with mild to moderate renal and hepatic insufficiency.
Interactions
No clinically significant drug
interactions were found. Compounds that have been studied in clinical trials
include cimetidine, warfarin, furosemide, digoxin, atenolol, indomethacin,
hydrochlorothiazide, amlodipine, and glibenclamide.
Valsartan is not extensively
metabolized, and clinically relevant drug interactions appear as induction or
inhibition. metabolic. it is not expected to produce the cytochrome P450
system. Although valsartan is highly bound to plasma proteins, in vitro studies
have not shown any interaction at this level with molecules that are highly
bound to a number of proteins (such as diclofenac, furosemide, and warfarin).
Simultaneous use of potassium-sparing diuretics (such as spironolactone,
triamterene, amiloride), potassium supplements, or potassium-containing salt
substitutes may lead to an increase in serum potassium. If you think it is
necessary to use a combination of drugs, caution is advised
Contraindications
Valsartan is contraindicated in
patients allergic to any component of this product.
Side Effects
Valsartan is generally well tolerated
and has few side effects. The most common side effects include headache,
dizziness, fatigue, abdominal pain, cough, diarrhea, and nausea. Patients may
also experience hyperkalemia, impotence, decreased kidney function, allergic
reactions, dyspnea, constipation, back pain, muscle cramps, rash, anxiety,
insomnia, and dizziness. If the patient is taking diuretics and valsartan at
the same time, hypotension may also occur.
Pregnancy
Pregnancy: Valsartan should not be
used during pregnancy because it can cause fetal injury or even death in the
second and third trimester. When pregnancy is detected, valsartan treatment
should be stopped as soon as possible.
Breastfeeding mothers: Whether
valsartan is excreted in human milk is unclear. Due to the possibility of
adverse reactions in breastfeeding infants, the importance of the drug to the
mother should be considered and the decision to stop breastfeeding or
medication should be stopped.
Precautions
Hepatic impairment: Since most of
valsartan is excreted by bile, patients with mild to moderate hepatic
impairment (including obstructive biliary disease) should be used with
caution.
Impaired renal function: Patients
with pre-existing impaired renal function may need to reduce or interrupt the
dose.
Heart failure and myocardial
infarction: Patients with heart failure and myocardial infarction should be
cautious when starting treatment.
Therapeutic Class
Angiotensin-ll receptor blocker
Storage Conditions
Store between 15-30° C. Protect from
moisture and heat.
