Yours

Mezaton is α-adrenergic; possesses vasoconstrictor activity.

Indications Mesatone

It is used to eliminate ophthalmic disorders:

• iridocyclitis, uveitis of the anterior subtype (therapy and prevention of the appearance of posterior commissures or asthenopia, and in addition, weakening of the exudation associated with the iris);
• dilation of the eye pupil to perform diagnostics during ophthalmoscopy and other procedures required to study the state of the posterior ophthalmic region, and with it during laser procedures and surgery of vitreo-retinal type;
• when performing provocative testing in persons with a narrow view of the angle of the anterior eye chamber and the presence of a suspicion of the development of  angle-closure glaucoma
• differential examination with the introduction of injections into the eyeball;
• the weakening of irritation and hyperemia during the "red eye" syndrome;
• combination therapy of accommodative spasm (children).

By parenteral administration for such disorders:

• reduced blood pressure;
• state of shock (including toxic and traumatic varieties of it);
• vascular insufficiency, sometimes developing due to intoxication with vasodilators;
• in the form of a vasoconstrictor with local anesthesia.

It can also be prescribed for administration by the intranasal method for a vasomotor or allergic rhinitis.

[1]

Release form

The release of the pharmaceutical substance is in the form of drops for the eyes, inside the bottle-droppers with a capacity of 5 ml.

In addition, it is realized in the form of injection fluid, inside ampoules with a capacity of 1 ml; The box contains 10 such ampoules.

Pharmacodynamics

Mezaton is an α-adrenostimulyator having an insignificant effect on cardiac β-adrenergic receptors. It cannot be considered catecholamine, because the drug has only 1 hydroxyl category inside its own aromatic core; it can increase blood pressure and narrow arterioles, which sometimes develops reflex bradycardia.

Compared with epinephrine or norepinephrine, the drug increases the level of blood pressure more smoothly, while its effect is longer, because it is not so much exposed to the catechol-O-methyltransferase component. Treatment using mezaton does not cause an increase in the values of the minute blood volume.

The drug has vasoconstrictor properties, similar to the effects of norepinephrine, but the effect is less strong and longer; At the same time, the drug does not have inotropic and chronotropic effects on the heart.

The instillation of the drug leads to a reduction in the pupillary dilatator, as a result of which it expands (and with it the smooth muscles of the conjunctival arterioles). The substance does not affect the activity of the ciliary muscle, because of which mydriasis is not accompanied by cycloplegia.

Drug exposure develops immediately after intravenous injection and lasts for the next 5-20 minutes. If the substance is injected s / c method, the duration of the effect is 50 minutes, and with a / m injection - 1-2 hours.

[2], [3], [4], [5], [6]

Pharmacokinetics

Phenylephrine can easily go inside the eye tissue, expanding the pupil for 10-60 minutes. A significant reduction of the pupillary dilator inside the moisture of the anterior eye chamber after 30-45 minutes after the instillation, allows you to detect parts of the leaf pigment of the iris; in this case, it is necessary to differentiate uveitis or penetration of the uniform blood components.

The exchange processes of phenylephrine develop inside the liver, and in addition to this the gastrointestinal tract (the enzyme catechol-O-methyltransferase does not participate in this).

The excretion of metabolic elements occurs through the kidneys.

[7], [8],

Dosing and administration

Drops for the eyes are used in the form of instillation - you need to dig one drop into the inside of the conjunctival sac.

The injection fluid is administered in a jet or intravenous, at low speed.

With collapse.

Drug administration through an IV drip, intravenously - 1% liquid (1 ml) is required, which is diluted in a 5% dextrose solution (0.25 or 0.5 l).

At the same time, 0.1, 0.3 or 0.5 ml of 1% liquid is diluted in 5% dextrose solution (20 ml) or 0.9% NaCl. If necessary, the introduction procedure can be repeated.

Dosage portions for i / m or s / c administration (for adults) are in the range of 0.3-1 ml of 1% liquid, 2-3 times a day. Adolescents older than 15 years of age (with a reduced level of blood pressure) to perform spinal anesthesia require the use of 0.5-1 mg / kg patient weight.

To narrow the vessels inside the mucous membranes and reduce the intensity of the symptoms of inflammation, you need to bury or lubricate the area with concentrated liquid - 0.125, 0.25, as well as 0.5 or 1%.

With local anesthesia.

To the anesthetic used in the form of a solvent (10 ml), it is required to add 0.3-0.5 ml of 1% liquid medication.

Adults with 1-fold i / m or s / c injection can enter a maximum of 10 mg of the substance; per day - a maximum of 50 mg of the drug. With intravenous injection, a single dose of a drug is equal to a maximum of 5 mg, and daily - 25 mg.

To prevent a repeated decrease in blood pressure values after discontinuation of the medication, it is necessary to reduce the dosage gradually (especially if this is done after performing a long infusion). Resume the infusion is allowed after the reduction of systemic indicators of blood pressure to 70-80 mm Hg.

Use Mesatone during pregnancy

It is possible to use Mezaton in pregnant women very carefully - in the presence of strict vital indications and under medical supervision (it is first necessary to evaluate the risks and benefits of the drug for the woman and the fetus).

At the same time, it was revealed that the introduction of vasoconstrictors during labor (in order to correct the decreased blood pressure indicators), as well as additions to local anesthetics in combination with medicines that stimulate uterine contractile activity (among them ergotamine with vasopressin, as well as ergometrine with metilergometryn), cause a persistent increase in blood pressure after delivery.

Contraindications

The main contraindications:

• pheochromocytoma;
• hypertrophy associated with obstructive cardiomyopathy;
• ventricular fibrillation;
• the presence of intolerance associated with drugs.

For ophthalmic procedures is not assigned in such cases:

• glaucoma, which has a closed-angle or narrow-angle character;
• significant disorders in the work of the cardiovascular system (among them aneurysm, heart disease, tachycardia and high blood pressure);
• insulin-dependent diabetes mellitus;
• hyperthyroidism;
• the presence of disturbances in the integrity of the bottom of the eye or disorders of tearing activity;
• congenital deficiency of the G6PD component or hepatic type of porphyria.

Caution with the use of drugs is required for such conditions:

• metabolic type of acidosis;
• hypoxia or hypercapnia;
• atrial fibrillation;
• increased values of blood pressure or hypertension within a small circle of systemic blood flow;
• gossip;
• aortic stenosis having a severe degree of intensity;
• acute stage of myocardial infarction;
• arrhythmia of the ventricles or tachyarrhythmia;
• occlusive vascular pathology (also its presence in history) during atherosclerosis, Raynaud’s syndrome, arterial thromboembolism, Buerger’s disease or diabetes mellitus, and also with vascular tendency to develop spasms, diabetic endarteritis and frostbite, as well as when combined with IMAO;
• introduction of general anesthesia (fluorotane);
• renal dysfunction;
• elderly people.

[9], [10], [11]

Side effects Mesatone

Among the side effects are:

• ventricular fibrillation, bradycardia, increased blood pressure, arrhythmia, palpitations, and cardialgia;
• feeling of great anxiety, fear or weakness, dizziness, insomnia, headaches;
• tremor, paresthesia, convulsions, cerebral hemorrhage;
• blanching of the skin on the face;
• signs of allergy, local appearance of a scab in case of penetration into the tissues and epidermal ischemia in the area of drug administration.

With the introduction of drops, negative signs may appear from the visual organs: hyperemia of a reactive nature, a feeling of discomfort, burning or irritation, and also visual blurredness, miosis of a reactive nature, tearing and an increase in the level of IOP.

[12], [13]

Overdose

In case of poisoning, extrasystole of the ventricles, a feeling of heaviness in the limbs and head, as well as short paroxysmal symptoms of ventricular tachycardia and a significant increase in blood pressure are noted.

An intravenous injection of α-blockers is performed (Phentolamine can be used). If a heart rhythm disorder occurs, it is recommended to inject β-blockers.

[14],

Interactions with other drugs

The use together with antihypertensive and diuretic drugs leads to a weakening of the antihypertensive properties of these drugs (guanethidine, mecamylamine and guanadrel with methyldopa).

The combination with phenothiazines or α-blockers (such as phentolamine) reduces hypertensive activity.

Introduction in combination with MAOI (among them selegilin and furazolidone with procarbazine), as well as with ergot alkaloids, methylphenidate, oxytocin, and besides tricyclics and adrenostimulants leads to a significant potentiation of pressor activity, as well as the arrhythmogenicity of the element phenylephrine.

Combining with β-adrenergic blockers weakens the pacemaker.

The use of reserpine leads to an increase in blood pressure, which develops due to the depletion of catecholamine depots located inside the adrenergic receptors, as a result of which the response to adrenomimetics increases.

Combined administration with anesthetics that have an inhalation form (such as isoflurane, enflurane with methoxyflurane, as well as halothane and chloroform) increases the risk of developing severe arrhythmias affecting the atria or ventricles - because this greatly increases the sensitivity of the myocardium relative to sympathomimetics.

Use in combination with ergotamine, oxytocin or ergometrine, as well as doxapram or methylergometrine increases the intensity of the vasoconstrictor effect.

Introduction together with nitrates weakens their antianginal activity, which reduces the pressure of sympathomimetics and the risk of a decrease in blood pressure.

With simultaneous use of Mezaton and thyroid hormones, mutual potentiation of their effects develops with the risk of a coronary insufficiency, which is more likely in people with coronary atherosclerosis.

The mydriatic activity of phenylephrine is potentiated by atropine.

[15], [16], [17],

Storage conditions

Mezaton is required to be kept in a dark and closed place from small children. Temperatures - not higher than + 25 ° C.

[18]

Shelf life

The mezaton in the form of an injection liquid can be applied for a 3-year term from the moment the therapeutic substance is produced. The shelf life of the drops is 24 months (at the same time, after opening the bottle, it can be used a maximum of 14 days).

Application for children

In pediatrics, prescribed with caution. Drops of the drug should not be prescribed to newborns with low weight.

[19]

Analogs

Analogues of the drug are such substances - spray Nazol kids and Irifrin 2.5%.