Arterial hypertension (especially essential and renovascular) – the drug is usually used in combination with other antihypertensive agents if the response to treatment with first-line drugs is unsatisfactory or if they are contraindicated.
active substance: guanfacine;
1 tablet contains 1 mg of guanfacine (corresponding to 1.15 mg of guanfacine hydrochloride);
excipients: stearic acid, povidone, microcrystalline cellulose, lactose monohydrate.
Estulik Dosage form
Main physical and chemical properties: white or yellowish-white, round, flat tablets with a bevel, with a line on one side and engraved with a stylized letter “E” on the other side, without or almost odorless.
Antihypertensive drugs. Central antiadrenergic agents. Imidazole receptor agonists. Guanfacine. ATX code C02A C02.
Guanfacine, the active ingredient in Estulik® tablets, is primarily a centrally acting α2-receptor agonist, an antihypertensive agent due to its ability to reduce sympathetic activity. Its agonistic effect on peripheral presynaptic α2-receptors may contribute to the antihypertensive effect, but primarily guanfacine has the ability to induce bradycardia. Guanfacine reduces the release of norepinephrine at both central and peripheral synapses, thereby reducing total peripheral resistance and heart rate. Cardiac output does not change as a decrease in heart rate is accompanied by an increase in heart rate. Guanfacine does not affect the regulation of blood pressure at rest or during exercise. It has almost no effect on glomerular filtration rate. Guanfacine reduces plasma renin activity as well as plasma norepinephrine levels, but these effects are not closely related to the degree of antihypertensive effect. Guanfacine does not affect the circulation of dopamine. Due to its pharmacological properties, guanfacine does not adversely affect the underlying disease in patients with chronic obstructive pulmonary disease, heart or kidney failure, grade I atrioventricular block, diabetes mellitus, gout or hyperlipidemia suffering from arterial hypertension.
After oral administration, guanfacine is rapidly and almost completely absorbed in the gastrointestinal tract. Its first-pass metabolism has no clinical significance.
Bioavailability is approximately 80%. Plasma protein binding is 60-70%.
The apparent volume of distribution is 6.3 l / kg. The maximum concentration in blood plasma is reached approximately in 1-4 hours after drug administration. The pharmacokinetic parameters of guanfacine are linear. It is partially metabolised in the liver (sulphate and glucuronide conjugation). With normal renal function, almost 80% of the dose is excreted by the kidneys, by glomerular filtration and tubular secretion. Almost 50% (40-75%) of the amount excreted by the kidneys is excreted unchanged in the urine, while the rest is excreted as metabolites. The half-life is 17-18 hours, on average – 10-30 hours. The duration of action of the drug is more than 24 hours when taking the drug once a day.
Guanfacine can pass through the placenta and into breast milk.
Some groups of patients
The half-life of guanfacine in elderly patients is near the upper limit of the normal range, but dose adjustment is usually not required.
In renal insufficiency, the clearance of guanfacine is reduced, however, apparently due to increased metabolism in the liver, the level of guanfacine in plasma increases, but only slightly, so usually no dose adjustment is required.
Patients on dialysis do not require an additional dose of guanfacine, as guanfacine is virtually not removed by dialysis (approximately 2.4% of the absorbed amount can be removed by dialysis).
In patients with hepatic insufficiency, guanfacine does not accumulate in the body.
Hypertension (especially essential and renovascular) – the drug is usually used in combination with other antihypertensive drugs, if the response to treatment with first-line drugs is unsatisfactory or if they are contraindicated.
Hypersensitivity to the active substance or to any of the excipients; cardiogenic shock, collapse, hypotension; concomitant use with α2-adrenoceptor antagonists (eg, yohimbine, phentolamine).