Reserpine drug interactions

Drug interactions Catecholamine-depleting drugs such as reserpine may have an additive effect in combination with betablockers. Drugs that inhibit CYP2D6 (quinidine, fluoxetine, paroxetine, and propafenone) increase metoprolol concentration. 

VMATs are irreversibly inhibited by the potent antihypertensive drug reserpine. The depressive effects of reserpine helped to formulate the original monoamine hypothesis of affective disorders. Reseipine also appears to interact with the transporters near the site of substrate recognition. Tetrabenazine, which is used in treatment of movement disorders, inhibits VMAT2 much more potently than VMAT1, consistent with the less hypotensive action of this agent. 

Levodopa interacts with many different drugs. When levodopa is used with phenytoin, reserpine, and papaverine, there is a decrease in response to levodopa The risk of a hypertensive crisis increases when levodopa is used with the monoamine oxidase inhibitors (see Chap. 31). Foods high in pyridoxine (vitamin B6) or vitamin B6 preparations reverse the effect of levodopa However, when carbidopa is used with levodopa, pyridoxine has no effect on the action of levodopa hi fact, when levodopa and carbidopa are given together, pyridoxine may be prescribed to decrease the adverse effects associated with levodopa... 

Other drug effects that decrease DA activity also support this position. Thus, when DA synthesis is blocked by a-methyl- p-tyrosine (AMPT), the dose necessary for an antipsychotic effect is reduced (i.e., the dose-response curve is shifted to the left by the interaction between dopamine and AMPT). A drug such as reserpine that can deplete DA stores also has relatively mild antipsychotic properties. Also, aripiprazole, which has D 2 presynaptic agonist properties, decreases the production of DA, as well as blocking D2 postsynaptic receptors. 

This phenomenon is one of the pillars of the biogenic amine hypothesis of depression (see Suicide later in this chapter). An intriguing finding with reserpine is that those susceptible to a depressive syndrome while on this agent also have an increased likelihood of a personal or family history of MDD, in comparison with those who are not susceptible. This finding suggests an interaction between a constitutional predisposition and the biochemical effects of this drug. Because depression is a... 

So far we have treated activation and modulation as separate processes. We will want to preserve that distinction even now as we explore their close interaction. In mania, whether it be driven by stimulants or by high levels of endogenous aminergic neuromodulator, the activation level is raised and the tendency to sleep is lowered. In depression, whether it comes in response to amine depletion by drugs like reserpine or to low levels of endogenous neuromodulators, the activation level is always low and the tendency to sleep may be high. There are notable exceptions to these rules, especially in depression, which is sometimes associated with extreme motor agitation and severe insomnia. 

Interactions of sympathomimetics with other vasoactive drugs are complex. Some drugs block the reuptake mechanism for noradrenaline in adrenergic nerve terminals and potentiate the pressor effects of noradrenaline e.g. cocaine, tricyclic antidepressants or highly noradrenaline-selective reuptake inhibitors such as roboxetine. Others deplete or destroy the intracellular stores within adrenergic nerve terminals (e.g. reserpine and guanethidine) and thus block the action of indirect S5unpathomimetics. 

Most antihistamines possess anticholinergic properties that by themselves are of minor intensity but may increase considerably if given together with MAOIs. Interactions of MAOIs with antihypertensives (e.g., reserpine-type drugs) and oral antidiabetic drugs, as well as insulin and L-dopa, have all been encountered. It can be seen why MAO inhibitors are not viewed today as initial therapy except possibly in atypical depression. Certain panic and phobic reactions respond well. An important indication would be in case of therapeutic failures with the tricyclic or other heterocyclic antidepressants. 

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