The range of clinical effects of farmapram (alprazolam), like other benzodiazepines, is based on modulation of GABAA-receptors, followed by secondary neurochemical and hormonal rearrangements. It is discussed that stimulation of GABA-receptors leads to changes in the activity of the monoaminergic system. At the same time, a weakening of the activity of the hypothalamic-pituitary-adrenal system is described. Prolonged use of benzodiazepines, including farmapram, leads to decreased sensitivity of GABA receptors. This is the basis for the development of the addictive phenomenon. However, it is believed that tolerance is not formed to all effects of benzodiazepines. It is unconditional with regard to the hypnotic, myorelaxant and anticonvulsant effects, and is disputed with regard to the anxiolytic effect. Indeed, many patients take alprazolam for long periods of time to alleviate anxiety without diminishing the efficacy of treatment.
It is believed that the antidepressant effect of farmapram (alprazolam) is realized due to its selective action on a2- and a3-subunits of GABAA-receptors, which is absent in the spectrum of psychotropic activity of other tranquilizers, whose action is associated with stimulation of GABAA-receptors. The data about bipolarity of neurochemical action of alprazolam depending on an initial emotional state are interesting: at depression the drug promotes strengthening of noradrenergic activity (especially in prefrontal cortex and hippocampus), and at anxiety leads to its weakening.
Benzodiazepines have no affinity for dopamine, serotonin, cholinergic, adrenergic, histamine and other CNS and autonomic nervous system receptors. This determines the absence of side effects during their use, so typical for other classes of psychotropic drugs. Average period of reaching maximum concentration of alprazolam in blood is 1.5 hours. Due to high lipophilicity, the drug, like other benzodiazepines, penetrates well through the blood-brain barrier, which explains the rapid onset of its therapeutic effect. Farmapram (Alprazolam) relates to benzodiazepines of medium duration of action: average half-life of the drug is 11 hours.
After oral administration, the active component is well absorbed in the digestive tract and reaches peak plasma concentrations within 1-2 hours. The bioavailability of the drug farmapram (alprazolam) is about 80%. Plasma concentrations increase proportionally with increasing doses of alprazolam. About 80% of the dose taken is bound to plasma proteins. Alprazolam penetrates the blood-placental and blood-brain barrier and is detected in breast milk. Equilibrium concentrations of alprazolam in plasma are established on the second or third day of therapy. It is metabolized mainly in the liver to form the pharmacologically active substance (alpha-hydroxyl metabolite). It is excreted mainly by the kidneys in the form of compounds with glucuronic acid; the elimination half-life of alprazolam reaches 11-16 hours. Alprazolam practically does not cumulate in the body.