2. RECEPTORS Cellular component to which the drug binds and through which initiates the effect Ionotropic: ligand gated Ionic Channels, activation leads to rapid and transient increase in membrane permeability. Causes excitation or inhibition of the post synaptic membrane. e.g. GABA A receptors Quick response Metabotropic; Produced slower response involving G protein which bind to the intracellular portion of the receptor and activate a second messenger. This will altered the phosphorylation state of key proteins rendering them active or inactive e.g. antipsychotics, antidepressants

9. TYPES OF ADVERSE REACTIONS

10. MECHANISM OF ACTION FOR SIDE EFFECTS Agitation ALPHA2 Blockade, 5HT 2A/2C stimulation Akathisia D2 antagonism, 5HT2A stimulation Delirium anticholinergic effect (muscarinics) EPSE D2 blockades Insomnia alpha 1 stimulation, 5HT2A Stimulation (hence SSRIs) Amnesia antimuscarinics and GABA stimulation Hyperprolactinaemia D2 blockade, 5HT1A stimulation Sweating Cholinergic effect and increases with NARIs Anorgasmia Alpha 1 antagonism, 5HT2A/2C stimulation (delayed ejaculation on SSRIs Impotence alpha 2 blockade, 5HT2A/2C stimulation (also low libido)

11. WEIGHT GAIN Cannot be explained by a single mechanism of action Antihistaminic effect 5HT2A/2C antagonism Insulin resistance (Valproate and Olanzapine are noted) Genetic factors seems to be involved - 5HT2C receptor. Drugs with strong affinity for this receptors will have a greater impact on weight increase.