Modulation of neurochemical systems by psychotropic drugs in anxiety

Psychotropic drugs used in the treatment of anxiety disorders exert their therapeutic effects by modulating the activity of neurotransmitters and brain circuits that are considered dysfunctional in these conditions.

Their objective is to restore a neurochemical balance that allows a reduction of anxious symptoms.

Selective Serotonin Reuptake Inhibitors (SSRIs)

SSRIs are frequently the first line of pharmacological treatment for many anxiety disorders, including GAD, panic disorder, social anxiety, and OCD.

Mechanism of Action: These drugs selectively block the reuptake of serotonin into the presynaptic neuron.

Reuptake is a natural process by which the neurotransmitter released at the synapse is reabsorbed for reuse or degradation.

By inhibiting this process, SSRIs increase concentration and the duration of serotonin in the synaptic cleft, which enhances its effect on postsynaptic receptors.

This improvement in serotonergic neurotransmission, through long-term adaptations in brain circuits, is thought to contribute to a reduction in anxiety and an improvement in mood.

It usually takes several weeks for their full anxiolytic effect to be reached.

Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)

SNRIs, such as venlafaxine or duloxetine, are also effective for several anxiety disorders.

Mechanism of Action: They work by inhibiting the reuptake of both serotonin and norepinephrine.

By increasing the availability of both neurotransmitters, they may have a broader spectrum of action.

Modulation of the noradrenergic system may be particularly useful for the physical symptoms of anxiety and for energy and motivation.

Benzodiazepines

Benzodiazepines are fast-acting anxiolytics.

Mechanism of Action: They bind to specific sites on GABA-A receptors in the brain, enhancing the inhibitory effect of the neurotransmitter GABA.

By increasing neuronal inhibition, benzodiazepines produce a calming, sedative, muscle relaxant, and anxiolytic effect.

Their rapid onset of action makes them useful for the acute relief of anxiety or panic.

However, due to their potential for dependence, tolerance, and withdrawal symptoms, their long-term use is generally discouraged and they are reserved for short courses of treatment or occasional use.