Therapeutic Classifcation Notes (ANTIDEPRESSANTS)

General Indications Loss of energy and drive, guilt feelings and persistent feelings of sadness and depression. General Side-Effects Anticholinergic - dry mouth, blurred vision, urinary retention (especially in prostate hyper-trophy), constipation and confusional states. Tachycardia and static hypotension is particularly troublesome in the elderly. Sexual dysfunction may take the form of decreased libido, impaired erection or ejaculation. Weight gain is often seen and many of these patients develop a high frequency tremor. The initial dosage for the elderly should be about one third that used for the young adult. Interactions The tricyclics antagonize the action of the adrenergic neurone blocking drugs, e.g. guanethidine, anti-hypertensive effects with sudden rise in blood pressure. They may induce or aggravate cardiac arrythymias. MONOAMINE - OXIDASE - INHIBITORS (MAOI’S ) General Comments A drug free period of about 3 days is advised when changing from tricyclics to MAOI’s. When changing from MAOI’s to tricyclics 10 drug free days are recommended. Interactions May cause hypertensive reactions with tyramine containing foods e.g. cheese, broad beans, meat and vegetable extracts, yeast extracts and alcohol. Avoid simultaneous use of cough and cold remedies and nasal sprays because of interactions with the sympatho-mimetic i.e. adrenaline, ephedrine, neo-synephrine. Hypotensive crises may also occur when used with narcotic analgesics.