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Picamilon is a compound formed by reacting niacin with GABA. It was invented in Russia. Picamilon is able to cross the blood-brain barrier and activate GABA receptors, producing an anxiolytic response. The niacin also acts as a strong vasodilator, helping to improve awareness.
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An essential role in the mechanism of action of Picamilon is its effect on nervous control of the cerebral circulation. It weakens changes in cerebral blood flow during the vasomotor reflex, considerably inhibits constrictor responses of vessels in the carotid and vertebrobasilar basins due to stimulation of afferent fibers of somatic nerves, and causes gradually developing inhibition of tonic and reflex activity in sympathetic nerves.
Neuropharmacological screening tests on Picamilon have demonstrated its tranquilizing properties in small doses. For instance, at a dose of l mg/kg, Picamilon prevents the negative consequences of emotional stress (in cats it normalizes the orienting reaction when disturbed by the response to rage and fear). Like diazepam, it has an inhibitory effect on motivated aggression, associated with fighting for territory in rats.
Investigation of Picamilon's effect on the threshold of intracranial self-stimulation showed that in higher doses (80 and 160 mg/kg), in contrast with small doses which have a tranquilizing effect, Picamilon lowered the "self-stimulation" threshold (like amphetamine and other drugs of abuse), but at the same time reduced the number of self-stimulation attempts made. The stimulating action of the drug also has been shown in general anesthesia. For instance, at a dose of 100 mg/kg, Picamilon reduced by 1.7 times the duration of the sedative effect of hexobarbital sodium and reduced by half the duration of thiopental anesthesia.
Unlike tranquilizer drugs (chlorodiazepoxide, diazepam, phenazepam), Picamilon does not induce muscle relaxation, drowsiness or lethargy. Clinicians have stated that the drug closely resembles vinpocetine (the ethyl ester of apovincamic acid), but comparison of the properties of the two compounds showed that Picamilon is superior.
Picamilon produces no allergenic, teratogenic, embryotoxic or carcinogenic effects. On this basis, the pharmacological committee of the Ministry of the Health (Russia) recommended clinical trials of Picamilon for cerebrovascular disturbances, as a daytime tranquilizer, as a stimulant in depressive and asthenic (weakening) states, and to improve physical and mental working capacity. Picamilon was studied in a large number of scientific facilities within Russia. The total number of patients under observation was 984. Picamilon tablets were prescribed two to three times a day at a dose of 0.02 to 0.05 grams, and in a daily dose of 0.04 to 0.3 grams. Courses of treatment lasted from two weeks to one-and-a-half months.
The effectiveness of treatment was assessed by clinical and laboratory tests. Cerebral blood movements were evaluated by objective methods, including echopulsography, echoencephalography, rheo-encephalography, ultrasonic scanning, biomicroscopy of the conjuctiva, and electroencephalography.
In patients with acute cerebrovascular disturbances, improvement occurred on the fourth or fifth day, when the severity of neurologic symptoms was reduced. Later, headache, dizziness, noise in the head and memory disorders were reduced, motor and speech disorders began to regress rapidly, sleep improved, and irritability, emotional stress and anxiety were reduced. The velocity of cerebral blood flow was increased.
Administration of Picamilon to patients suffering from the results of cerebrovascular disturbances (more than a month later) proved effective after the second or third day of treatment. The patients' emotional background, speech and memory were improved, and levels of enzyme activity (aspartate transaminase, alanine transaminase, and lactate dehydrogenase) and lactate concentration were restored to normal.
Scientists who studied the effects of GABA derivatives on the development of toxic cerebral edema (fluid on the brain) showed that Picamilon in specific doses prevented the development of edema.
In chronic cerebral insufficiency, Picamilon improved the mood and memory of the patients, reduced irritability and tearfulness, abolished autonomic vascular manifestations, and reduced metabolic disturbances. In patients with memory disorders (global amnesia), considerable improvement in memorization and recall was observed on the fifth to seventh day of treatment, and the patients were able to return to work.
In patients with astheno-neurotic anxiety and depression, activation of mental functions and motor activity was observed, including improved speed and quality of operative activity, concentration of attention and mood, relief of anxiety, improved working capacity, and so on. The use of Picamilon in depression, along with moderate doses of tricyclic antidepressants, enabled the doses of the latter to be reduced. In patients with alcoholism, Picamilon abolished many withdrawal symptoms, especially apathy, weariness and lethargy. The patients later become more tranquil, less fussy and anxious, and their working capacity improved.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Picamilon". A list of authors is available in Wikipedia.|