6546153
Description
Flashcards by Andrew Street, updated more than 1 year ago
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Created by Andrew Street
about 8 years ago
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| Question | Answer |
| Give eg's of & indications for tricyclics. | eg's: amitriptyline, lofepramine Indications: • Moderate-to-severe depression - where 1st line SSRI's are ineffective • Neuropathic pain- not licensed for this indication |
| MOA of tricyclics. | Tricyclic antidepressants inhibit neuronal reuptake of serotonin (5-HT) & noradrenaline from the synaptic cleft, thereby increasing their availability for neurotransmission. This appears to be the mechanism by which they improve mood & physical Sx in moderate-to-severe (but not mild) depression & probably accounts for their effect in modifying neuropathic P. Tricyclic antidepressants also block a wide array of receptors, including muscarinic, histamine (H1), α-adrenergic (α1 and α2) and dopamine (D2) receptors. This accounts for the extensive adverse effects profile that limits their clinical utility. |
| SE's of tricyclics. | • Blockade of antimuscarinic receptors causes dry mouth, constipation, urinary retention & blurred vision • Blockade of H1 & α1 receptors causes sedation & hypotension • Arrhythmias • ECG changes - inc prolongation of the QT & QRS durations • Convulsions • Hallucinations • Mania • Blockade of dopamine receptors can cause breast changes & sexual dysfunction & rarely causes extrapyramidal symptoms (tremor & dyskinesia) • Extremely dangerous in OD - can cause hypotension, arrhythmias, convulsions, coma, resp failure, death • Sudden withdrawal - GI upset, neurological & flu like Sx, sleep disturbance |
| CI's, cautions, & important interactions of tricyclics. | CI's: • Should not be given with MAOI's Cautions: • Elderly • CVD • Epilepsy • Constipation • Prostatic hypertrophy • Raised intraocular pressure Important interactions: Tricyclic antidepressants should not be given with monoamine oxidase inhibitors as both drug classes increase serotonin & noradrenaline levels at the synapse & together they can precipitate HT & hyperthermia or serotonin syndrome (see Antidepressants, selective serotonin reuptake inhibitors). Tricyclic antidepressants can augment antimuscarinic, sedative or hypotensive adverse effects of other drugs. |
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