Ritalin/Ritalin LA

Ritalin/Ritalin LA Drug Interactions





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Full Prescribing Info
Drug Interactions
Anti-Hypertensive Drugs: Ritalin may decrease the effectiveness of drugs used to treat hypertension.
Drugs that Elevate Blood Pressure: Methylphenidate should be used with caution in patients being treated with drugs that elevate blood pressure due to the risk of severe hypertension (see Precautions).
Because of possible hypertensive crisis, Ritalin is contraindicated in patients being treated (currently or within the preceding 2 weeks) with non-selective, irreversible MAO-inhibitors (see Contraindications).
Halogenated Anaesthetics: There is a risk of sudden blood pressure increase during surgery. If surgery is planned, Ritalin should not be taken on the day of surgery.
Centrally Acting Alpha-2 Agonists (e.g. clonidine): Serious adverse events including sudden death have been reported in concomitant use with clonidine, although no causality for the combination has been established.
Dopaminergic Drugs: As an inhibitor of dopamine reuptake, Ritalin may be associated with pharmacodynamic interactions when coadministered with direct and indirect dopamine agonists (including DOPA and tricyclic antidepressants) as well as dopamine antagonists (antipsychotics, e.g. haloperidol). The coadministration of Ritalin with antipsychotics is not recommended because of the counteracting mechanism of action.
Pharmacokinetic Interactions: Ritalin is not metabolized by cytochrome P450 to a clinically relevant extent. Inducers or inhibitors of cytochrome P450 are not expected to have any relevant impact on Ritalin pharmacokinetics. Conversely, the d- and l- enantiomers of methylphenidate did not relevantly inhibit in vitro cytochrome P450 1A2, 2C8, 2C9, 2C19, 2D6, 2E1 and 3A.
Ritalin coadministration did not increase plasma concentrations of the CYP2D6 substrate desipramine.
Case reports have shown that methylphenidate may inhibit the metabolism of coumarin anticoagulants, anticonvulsants (phenobarbitone, primidone, phenytoin), phenylbutazone and tricyclic antidepressants (imipramine, desipramine), but pharmacokinetic interactions were not confirmed when explored at higher sample sizes. Reduction in the dosage of these drugs may be required when they are given concomitantly with methylphenidate.
Serious adverse events have been reported in concomitant use with clonidine, although no causality for the combination has been established. The safety of using methylphenidate in combination with clonidine or other centrally acting alpha-2 agonists has not been systematically evaluated.
Other specific drug-drug interaction studies with Ritalin have not been performed in vivo.
Effects on Laboratory Tests: Methylphenidate may induce false positive laboratory tests for amphetamines, particularly with immunoassays screen test.
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