Interaction between Amitriptyline and Lasmiditan
Major Synergy

ID DDInter78 and DDInter1027
Interaction Coadministration of lasmiditan and serotonergic agents may increase the risk of serotonin syndrome. Lasmiditan binds to the 5-HT(1F) receptor, where it presumably exerts therapeutic effects via agonist actions.
Management Caution is advised during coadministration of lasmiditan and agents that increase serotonin. Patients should be closely monitored for symptoms of the serotonin syndrome during treatment. Extra caution is advised when increasing the dosages of these agents. The potential risk for serotonin syndrome should be considered even when administering serotonergic agents sequentially, as some agents may demonstrate a prolonged elimination half-life.
References
Alternative for Amitriptyline -
Alternative for Lasmiditan -

Potential Metabolism Interactions

Substrate-Substrate Interaction：If more than one drug is metabolized by the same CYP, it is possible that its metabolism is inhibited because of the competition between the drugs. That means, it can be useful to lower the dosage of the drugs in the drug-cocktail because they remain longer in the organism than in monotherapy.
Inhibitor-Inhibitor Interaction：Combining two or more inhibitors of one CYP, should be compensated by lowering the dosage of these drugs because the metabolism is reduced and the drugs remain longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.
Inhibitor-Substrate Interaction：Combining drugs that have inhibitory effect and are substrates of one particular CYP, should be compensated by lowering the dosage. They rest longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.