Acebutolol

Acebutolol belongs to the beta-blocker family. It occupies the beta-adrenergic receptors, the sites normally bound by adrenaline and noradrenaline, the messengers that speed up the heart during exertion or stress. It is described as cardioselective: it targets primarily the beta-1 receptors, found mostly in the heart, rather than the beta-2 receptors of the bronchi and blood vessels. This selectivity remains relative, however, and is never complete.

By occupying the beta-1 receptors of the heart, acebutolol slows the heart rate, reduces the force of contraction and lowers blood pressure: the heart then works less. It also has a mild intrinsic sympathomimetic activity, meaning that it weakly stimulates the receptor while blocking it. As a result it slows the rhythm slightly less, with a heart rate about 3 beats per minute higher than with equipotent doses of propranolol or metoprolol. A membrane-stabilizing effect completes this action on the cardiac cell.

Acebutolol is prescribed for high blood pressure, where it lowers pressure by reducing the heart’s workload. It is also indicated for ventricular arrhythmias, in particular ventricular premature beats, those early contractions that disturb the rhythm. It is likewise used for angina pectoris, the pain that arises when the heart muscle lacks oxygen.

What these situations have in common is a heart beating too fast, too hard or in a disordered way, in a context where that becomes dangerous. By slowing the rhythm and reducing the muscle’s oxygen consumption, acebutolol eases this heart and spaces out the episodes. It does not cure the underlying disease, it controls its consequences for as long as it is taken.

Acebutolol is taken once or twice a day, preferably at the same time each day, with or without food. Food slightly lowers the peak concentration and slows absorption, without changing the total amount absorbed: the timing of the dose relative to meals therefore matters little. The molecule itself has a short half-life of 3 to 4 hours, but its active metabolite, diacetolol, persists 8 to 13 hours in the blood, which allows for dosing once or twice a day. If a dose is missed, it is taken as soon as possible, unless it is almost time for the next one, and it is never doubled.

One point calls for particular care: acebutolol must never be stopped abruptly. In patients with coronary disease, the sudden withdrawal of a beta-blocker has caused worsening of angina pectoris and, in some cases, heart attacks. Any interruption is done gradually and under medical supervision. This is also why regular renewal of the prescription is part of the treatment, just as much as taking the medicine itself.

In controlled clinical trials comparing acebutolol with placebo, fatigue is the most frequent effect: 11% of people on acebutolol versus 4% on placebo. Next come dizziness (6% versus 2%), headache (6% versus 4%), shortness of breath (4% versus 2%) and insomnia (3% versus 1%). Digestive complaints remain moderate and similar: constipation, diarrhea, dyspepsia and nausea each affect about 4% of people. Less commonly, mild edema (2%), visual disturbances (2%) and frequent urination (3%) are observed.

Two situations deserve separate attention. In people with diabetes, acebutolol can potentiate the hypoglycemia caused by insulin and mask one of its warning signs, tachycardia, while sweating and dizziness generally remain perceptible. In a person whose thyroid is overactive, beta-adrenergic blockade can likewise mask the tachycardia that betrays hyperthyroidism, and abrupt withdrawal of the drug may then trigger a thyroid storm. These two points explain why the treatment is monitored over time.

Several medicines change the action of acebutolol. Non-steroidal anti-inflammatory drugs can blunt its effect on blood pressure. Digoxin and acebutolol both slow conduction between the atria and the ventricles as well as the heart rate: combining them increases the risk of bradycardia. Medicines that deplete the body of its catecholamines, such as reserpine, can add to the beta-blocker and accentuate the fall in rhythm and pressure.

Breathing also comes into play: in people with asthma or COPD, a beta-blocker is generally not advised, because the cardioselectivity of acebutolol is not absolute and bronchospasm remains possible. As regards elimination, acebutolol leaves the body 30 to 40% through the kidneys and 50 to 60% through the bile and the stool. In renal failure, diacetolol accumulates and the dose must be reduced, which laboratory monitoring and clinical examination make it possible to adjust.

Food touches the same ground as your treatment, in particular sleep and the energy of the cells. Beta-blockers that target the beta-1 receptors also act on the pineal gland: in humans, atenolol reduces the nocturnal secretion of melatonin in a dose-dependent relationship, which can affect falling asleep. Yet the plate provides very little melatonin, and the body makes most of it itself during the night. When the beta-blocker slows this production, food alone does not make up the difference.

On the side of cellular energy, studies have shown that one beta-blocker, propranolol, inhibits enzymes that depend on coenzyme Q10. This coenzyme is found mainly in oily fish and meats, but the body produces the greater part of it. For the rest, the plate keeps all its usefulness: the magnesium of spinach, almonds, pumpkin seeds and dark chocolate, the vitamin B6 of bananas and fish. In addition to your treatment, never in its place, a targeted intake makes sense where food reaches its limit.