Psychopharmacology (Proceedings)

Aug 01, 2011

Synapse physiology

• Neurotransmitter – remain within the synapse to transmit action potential to post synaptic membrane
• Neuromodulator – released into synapse in large amounts and diffuse out of synapse to affect the activity of numerous neurons
• Hormone – released by specialized cells into the circulation and affects a wide variety of cells, including neurons.


• Junction of pre-synaptic axon terminal button and the membrane of the post-synaptic neuron

Termination of Post Synaptic Potential

• Enzymatic Deactivation – For example, the activation of acetyl cholinesterase to neutralize the activity of acetylcholine.
• Reuptake – Reabsorption of neurotransmitter into the pre-synaptic cytoplasm via membrane channels.

Principle neurotransmitters

• GABA (gamma amino butyric acid) – inhibitory neurotransmitter. Potentiated by benzodiazepines.
• Glutamate – excitatory amino acid.
• Acetylcholine – Wide distribution in the body. Many drugs have anticholinergic side effects (dry mouth, urine/fecal retention, cardiac arrhythmias)
• Monoamines (dopamine, norepinephrine, serotonin) found in midbrain, hypothalamus and limbic system. Tyrosine is precursor for Dopamine and Norepinephrine. Tryptophan is the precursor for Serotonin.

Considerations when using psychoactive pharmaceuticals

• Drugs are rarely the sole treatment method
• Rule out medical issues (pre and post treatment exams and lab work)
• Allow ample time for drug to take effect. Maximum effect for the TCA's, SSRI's, Selegiline and Buspirone can take as long as 6-8 weeks.
• Safety factors, side effects, lack of FDA approval. Consider signed informed consent
• Clear client communication before and after dispensing medication
• Caution with combination drug therapy particularly with drugs effecting serotonin (SSRI's, TCA's and MAO's)
• Serotonin Syndrome – excessive levels of serotonin causing increased blood pressure, tremors, decreased mental state, hyperreflexia, hyperthermia and restlessness.
• Dosage form (tablet, liquid, transdermal), frequency, ease of administration
• Clear knowledge of a few drugs
• Drug trial
     - Lack of desirable effect then choose drug from alternate drug class
     - If beneficial but side effects then alternate drug from same class