Valproic acid

Benjamin Clanner-Engelshofen is a freelance writer in the medical department. He studied biochemistry and pharmacy in Munich and Cambridge / Boston (USA) and noticed early on that he particularly enjoyed the interface between medicine and science. That is why he went on to study human medicine.

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The active ingredient valproic acid is used to treat epilepsy and seizures and to stabilize mood in bipolar disorders. In addition, because of its wide spectrum of activity, it is also being studied for the treatment of other diseases such as hereditary diseases, HIV and cancer. Here you can read everything you need to know about the effects and use of valproic acid, side effects and interactions.

This is how valproic acid works

In the human brain, the nerve cells (neurons) communicate with each other by releasing messenger substances (neurotransmitters) that are perceived by neighboring nerve cells via certain docking points (receptors).This signal transmission via neurotransmitters can either excite or inhibit the following nerve cell - depending on the type of neurotransmitter and the type of receptor. Glutamic acid, for example, is an exciting ("excitatory") neurotransmitter, GABA (gamma-aminobutyric acid) an inhibiting ("inhibitory") neurotransmitter in the brain.

In people with epilepsy and seizures, the nerve cells in the whole brain or only in individual areas of the brain are excessively excitable. They develop massive waves of excitation signals - either spontaneously or as a result of certain triggers. This can trigger the classic symptoms of epilepsy: cramps with tense or fast moving (twitching) muscles and / or loss of consciousness.

Active ingredients such as valproic acid on the one hand inhibit the exciting neurotransmitter effects and at the same time strengthen the effect of the inhibiting messenger substance GABA. This depressant effect of valproic acid also explains why it can alleviate manic phases in patients with bipolar disorder.

Uptake, breakdown and excretion of valproic acid

After ingestion, valproic acid is absorbed in the intestine and reaches the brain via the bloodstream, where it crosses the blood-brain barrier without any problems. The concentration of valproic acid in the brain reaches about ten percent of the concentration in the blood.

The active ingredient is broken down in the liver into many different metabolic products, some of which may also be effective against seizures. These are mainly excreted in the urine. About twelve to 16 hours after ingestion, the concentration of the active ingredient in the blood has halved again.

When is valproic acid used?

The active ingredient valproic acid is used to treat many forms of epilepsy. These include, for example:

• generalized seizures in the form of absences (petit mal seizure with a short pause in consciousness)
• generalized seizures in the form of tonic-clonic seizures (grand mal seizures with loss of consciousness, fall, spasms and twitching of muscle groups)
• partial seizures of a complex nature with impaired consciousness

Valproic acid can also be used together with other active ingredients in other forms of epilepsy.

Valproic acid is also approved for the treatment of manic episodes in bipolar disorder when the active ingredient lithium is not tolerated or cannot be used for other reasons. The active ingredient can also be taken to prevent manic episodes.

Valproic acid is usually used for a longer period of time, but it can also only be used for short-term treatment in manic phases.

This is how valproic acid is used

Valproic acid and its more water-soluble sodium or calcium salt (often just called "valproate") are offered as tablets, tablets with extended release tablets (prolonged release tablets), gastro-resistant tablets as well as oral and injection solutions.

Long-term treatment with valproic acid is mostly oral dosage forms, with the oral solution being reserved for children under six years of age and patients with swallowing disorders. Treatment is started with a low dose, which is gradually increased over the course of a few weeks. Usual doses for adults are 1000 to 1800 milligrams of valproic acid (equivalent to about 1200 to 2100 milligrams of sodium valproate). The total daily dose should be divided into two to four individual doses, depending on individual tolerance, in consultation with the doctor. The active ingredient should be taken on an empty stomach with a glass of water about an hour before meals.

What are the side effects of valproic acid?

The most common side effect is an increase in the concentration of ammonia in the blood. Taken alone, this increase is not a cause for concern, but high ammonia levels can trigger symptoms such as vomiting, impaired movement coordination, impaired consciousness, low blood pressure and an increased tendency to seizures. If such symptoms occur, therapy with valproic acid should be stopped or the dose should be reduced (in consultation with the doctor). One to ten percent of patients also experience valproic acid side effects such as a reduction in blood platelets (due to decreased formation in the bone marrow), an irregular menstrual cycle, hand tremors, abnormal sensations, headaches, fatigue, thinning hair, hair loss, increased or decreased appetite and an increase or decrease in weight.

What should be considered when taking valproic acid?

Medicines with the active substance valproic acid can be used to treat children from three years of age (in exceptional cases also below), in adolescents, adults and the elderly.

The combination with other medicines can decrease or increase the concentration of valproic acid in the body. For example, active ingredients such as mefloquine (anti-malarial agent) and carbapenems (antibiotics) can lower the valproic acid level in the body. Other active ingredients increase it, including anti-epilepsy agents (phenobarbital, phenytoin, primidone, carbamazepine, felbamate), gastric acid inhibitors (cimetidine), certain antibiotics (erythromycin, rifampicin) and the antidepressant fluoxetine.

Conversely, valproic acid can also influence the effect of other active substances. For example, it partially increases the effect of other anti-epileptic drugs, which is why the combined treatment should be carried out by an experienced doctor. Valproic acid can also increase the effect of anticoagulants and thus the tendency to bleed.

Valproic acid can potentially damage the liver. The liver function should therefore be checked before and during treatment in order to be able to react quickly if necessary. In the case of liver dysfunction, the doctor will carefully decide whether to use it.

Since valproic acid is teratogenic, pregnant and breastfeeding women must not be treated with valproic acid. In addition, adequate contraception should always be used during treatment with valproic acid.

How to get medicines containing valproic acid

Valproic acid is only available on prescription in any dosage and form of administration, i.e. only available after presentation of a doctor's prescription at the pharmacy.

Since when has valproic acid been known?

Valproic acid was first made by chemist Beverly Burton in 1881. Since the acid is very suitable for dissolving water-insoluble substances, it was often used in chemistry. It was not until 1962, when the French scientist Pierre Eymard was investigating plant ingredients, that the antispasmodic effect of the plant extracts was not due to the ingredients but to the solvent valproic acid. Valproic acid was approved as an anti-epilepsy agent in France as early as 1967. Since the active ingredient is no longer patent-protected, many pharmaceutical manufacturers now offer preparations with the active ingredient valproic acid.

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