Verapamil

Verapamil has antianginal and antiarrhythmic activity.

Indications Verapamil

It is used for the following disorders:

• supraventricular tachycardia;
• angina pectoris of a stable nature;
• angina pectoris, in which supraventricular rhythm disturbances are observed;
• sinus cardiac tachycardia;
• supraventricular extrasystole;
• atrial fibrillation;
• hypertensive crisis (by intravenous administration);
• increased blood pressure readings.

Release form

The therapeutic agent is released in tablets or dragees with a volume of 40 and 80 mg, as well as in tablets with a prolonged type of action (volume 0.24 g) and in a 2.5% solution for intravenous injections.

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Pharmacodynamics

Verapamil blocks the activity of Ca channels. The drug has antihypertensive, antianginal and antiarrhythmic effects.

The effect of the drug is based on blocking the activity of "slow" Ca channels located inside myocardial cells, smooth muscle vascular cells and the cardiac conduction system. At the same time, these channels are present inside the smooth muscles of the uterus, bronchi and urethra. The blockade leads to stabilization of the pathologically increased flow of calcium ions into the cells. By weakening the transmembrane entry of the Ca2+ element into cardiomyocytes, the drug reduces the heart rate and the force of myocardial contractions, which leads to a decrease in the oxygen demand of the myocardium.

Verapamil reduces the muscle tone of vascular membranes and leads to the expansion of arterioles, due to which the resistance inside the large circle of blood flow is weakened and the afterload is reduced. In addition, the drug also increases coronary circulation. It inhibits the processes of AV conduction and suppresses the automatic activity of the sinus node, due to which the drug can be used for supraventricular arrhythmias.

The drug has a more pronounced effect on the conduction system (AV and sinus node), and the effect on the vessels is weaker. The drug improves the secretory activity of the kidneys. It is necessary to remember that the drug aggravates the existing heart failure, and also causes AV block and severe bradycardia.

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Pharmacokinetics

The substance is almost completely absorbed when it enters the gastrointestinal tract. Blood Cmax values are recorded after 1-2 hours. Synthesis with blood protein is 90%.

It undergoes rapid intrahepatic metabolism. In case of course therapy, the effect of the drug is potentiated, because diclofenac and its metabolic products accumulate inside the body.

The half-life after a single use is 3-6 hours, and in case of prolonged use it reaches 12 hours. Excretion is carried out by the kidneys (approximately 74%).

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Dosing and administration

Conventional tablets for tachycardia or angina are taken orally before meals, 3 times a day, in a dose of 40-80 mg. To reduce high blood pressure, the drug should be taken 2 times a day (the daily dose in this case can reach 0.48 g).

Children under 5 years of age are required to take 40-60 mg of the drug per day.

Tablets with a prolonged type of action at elevated blood pressure values are taken in the morning in a portion of 0.24 g. It is recommended to start therapy with a reduced portion - 0.12 g 1 time per day. Then, after 14 days, the dosage is increased. It can also be increased to 0.48 g per day (2 times with a 12-hour interval). If it is necessary to conduct a long-term treatment cycle, it is prohibited to use more than 0.48 g of the drug per day.

To stop the development of a hypertensive crisis, the drug is administered intravenously by jet method - in the amount of 5-10 mg. In case of paroxysmal rhythm disorders, the dosage and method of administration are similar. If there is no result, the same portion is administered again after 20-30 minutes. For maintenance procedures, the drug is administered intravenously through a dropper (NaCl or dextrose solution is used). The size of a 1-time intravenous portion for a child aged 1-5 years is 2-3 g of the substance.

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Use Verapamil during pregnancy

At the moment, there is no information about the feto- and embryotoxicity of the drug. It can be used by pregnant women, but only in cases where the probable benefit is more expected than the development of complications. But at the same time, it is often prescribed during pregnancy. There are both obstetric and medicinal indications for its use.

Obstetric:

• risk of premature labor (in combination with other drugs);
• fetoplacental insufficiency;
• nephropathy developing in pregnant women.

In case of risk of premature birth, the medicine is used together with Ginipral; Verapamil should be taken a little earlier – 20-30 minutes. Reviews show that the use of Ginipral does not always lead to tachycardia, which allows you to refuse the use of Verapamil, but it is usually still necessary.

Because the drug affects calcium metabolism, it is often used in situations where there is a risk of premature labor. It has been found that tocolytic treatment can only be performed using agents that block Ca channels. After their oral administration, the amplitude of uterine contractions is significantly reduced (sometimes to the point of complete cessation of this activity).

In the case of a mild stage of nephropathy, monotherapeutic use of drugs is possible, and in the development of preeclampsia, combined methods are used, including magnesium sulfate (has a diuretic, anticonvulsant and antihypertensive effect), taking 80 mg of Verapamil per day and other medications.

Therapeutic:

• arrhythmia (this includes supraventricular tachycardia);
• increased blood pressure values. This is one of the antihypertensive drugs used in pregnant women (and can be used for a long time), although it is rarely prescribed to pregnant women as a basic antihypertensive drug;
• angina pectoris.

Comments from women who used the medication during pregnancy show that it is effective, tolerated without complications when used in medicinal doses, and does not have a negative impact on the fetus.

In postnatal analysis, women who used the drug in the first trimester did not show an increase in the incidence of birth defects associated with its use in the infant. Also, no negative manifestations were found in the infants of women who took Verapamil in the second and third trimesters.

Contraindications

Main contraindications:

• severe degree of bradycardia;
• severe left ventricular dysfunction;
• having 2-3 degree AV block;
• the presence of intolerance to the medication;
• decreased blood pressure values;
• SSSU.

Caution is required when used in individuals with 1st degree AV block, CHF, bradycardia, sinoatrial block, renal or hepatic insufficiency, and in the elderly.

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Side effects Verapamil

Common side effects include constipation, nausea, weight gain, a sharp decrease in blood pressure, bradycardia, flushing of the skin on the face, headaches, and dizziness.

Less common symptoms include: fatigue, nervousness or lethargy, rash, diarrhea, itching, gingival hyperplasia, galactorrhea, and in addition, pulmonary edema, third-degree atrioventricular block (if given intravenously at high speed), gynecomastia, agranulocytosis, arthritis, thrombocytopenia, and peripheral edema.

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Overdose

Drug poisoning causes SA or AV block, asystole, bradycardia, or decreased blood pressure.

First, gastric lavage and administration of sorbents are performed. If conduction disorders are observed, atropine, 10% calcium gluconate, isoprenaline and plasma-substituting substances are administered intravenously. It is recommended to use a pacemaker. To increase the blood pressure level, α-adrenergic stimulants are used.

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Interactions with other drugs

Drugs that inhibit CYP3A4 activity decrease verapamil levels; grapefruit juice, on the contrary, increases its plasma levels.

The drug increases plasma levels of cyclosporine, quinidine with carbamazepine, ethyl alcohol, theophylline and CG. In addition, it increases the likelihood of developing a neurotoxic effect of Li+ agents.

The level of bioavailability of the drug increases by 50% when combined with cimetidine, which sometimes requires a reduction in its dosage.

Rifampicin significantly reduces the bioavailability of the drug.

Combined use with inhalation painkillers increases the likelihood of developing heart failure, bradycardia and AV block.

Simultaneous administration of the drug with β-blockers increases the severity of myocardial contractility weakening, and in addition increases the likelihood of AV conduction disorders and the occurrence of bradycardia.

When combined with α-blockers, the antihypertensive effect is potentiated.

The negative inotropic effect is cumulative when administered together with flecainide and disopyramide. These agents are prohibited for use within 2 days before and 1 day after the administration of Verapamil.

The drug potentiates the activity of peripheral muscle relaxants.

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Storage conditions

Verapamil must be kept at temperatures no higher than 25°C.

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Shelf life

Verapamil is permitted to be used for a period of 5 years from the date of manufacture of the pharmaceutical product.

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Analogues

Analogues of the therapeutic substance are the medications Isoptin, Riodipine, Nifedipine with Kaveril, and in addition Finoptin, Amlodipine, Nimodipine and Lekoptin with Nifedipine Retard, Gallopamil and Nicardipine.

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Reviews

Verapamil is often used for therapy of combined disorders (atrial fibrillation combined with supraventricular tachycardia of a paroxysmal nature and elevated blood pressure). Patient reviews indicate that the drug is quite effective and at the same time inexpensive.

Among the disadvantages, the development of negative signs is highlighted - usually this is constipation, bradycardia and flushing of the skin of the face.