Note
Increased risk of toxicity with bone marrow suppression drugs .
ACE Inhibitors: enhanced hypotensive effect when antipsychotics given with ACE inhibitors.
Adrenergic Neuron Blockers: enhanced hypotensive effect when phenothiazines given with adrenergic neurone blockers.
Adsorbents: absorption of phenothiazines possibly reduced by kaolin.
Alcohol: increased sedative effect when antipsychotics given with ethanol and drugs containing ethanol, may cause respiratory depression.
Alpha-blockers: enhanced hypotensive effect when antipsychotics given with alpha-blockers.
Anaesthetics, General: enhanced hypotensive effect when antipsychotics given with general anaesthetics.
Analgesics: enhanced hypotensive and sedative effects when antipsychotics given with opioid analgesics.
Angiotensin-II Receptor Antagonists: enhanced hypotensive effect when antipsychotics given with angiotensin-II receptor antagonists.
Antacids: absorption of phenothiazines and sulpiride reduced by antacids.
Anti-arrhythmics: increased risk of ventricular arrhythmias when antipsychotics that prolong the QT interval given with anti-arrhythmics that prolong the QT interval.
Antibacterials: increased risk of ventricular arrhythmias when haloperidol, phenothiazines or zuclopenthixol given with moxifloxacin—avoid concomitant use.
Antidepressants: antipsychotics increase plasma concentration of tricyclics—possibly increased risk of ventricular arrhythmias; increased risk of antimuscarinic side-effects when phenothiazines given with tricyclics.
Antidiabetics: phenothiazines possibly antagonise hypoglycaemic effect of sulphonylureas.
Antiepileptics: antipsychotics antagonise anticonvulsant effect of carbamazepine, ethosuximide, oxcarbazepine, phenytoin, primidone and valproate (convulsive threshold lowered).
Antimuscarinics: plasma concentration of phenothiazines reduced by antimuscarinics, but risk of antimuscarinic sideeffects increased.
Antipsychotics: increased risk of ventricular arrhythmias when pimozide given with phenothiazines— avoid concomitant use.
Antivirals: plasma concentration of antipsychotics possibly increased by ritonavir.
Anxiolytics and Hypnotics: increased sedative effect when antipsychotics given with anxiolytics and hypnotics.
Atomoxetine: increased risk of ventricular arrhythmias when antipsychotics that prolong the QT interval given with atomoxetine .
Barbiturates: antipsychotics antagonise anticonvulsant effect of barbiturates (convulsive threshold lowered).
Beta-blockers: enhanced hypotensive effect when phenothiazines given with beta-blockers; increased risk of ventricular arrhythmias when amisulpride, phenothiazines, pimozide, sertindole or sulpiride given with sotalol.
Calcium-channel Blockers: enhanced hypotensive effect when antipsychotics given with calciumchannel blockers.
Clonidine: enhanced hypotensive effect when phenothiazines given with clonidine.
Diazoxide: enhanced hypotensive effect when phenothiazines given with diazoxide .
Diuretics: enhanced hypotensive effect when phenothiazines given with diuretics.
Dopaminergics: increased risk of extrapyramidal sideeffects when antipsychotics given with amantadine; antipsychotics antagonise effects of apomorphine, levodopa and pergolide; antipsychotics antagonise hypoprolactinaemic and antiparkinsonian effects of bromocriptine and cabergoline; avoidance of antipsychotics advised by manufacturer of pramipexole, ropinirole and rotigotine (antagonism of effect) .
Lithium: increased risk of extrapyramidal side-effects and possibly neurotoxicity when clozapine, flupentixol, haloperidol, phenothiazines or zuclopenthixol given with lithium.
Memantine: effects of antipsychotics possibly reduced by memantine.
Methyldopa: enhanced hypotensive effect when antipsychotics given with methyldopa (also increased risk of extrapyramidal effects).
Metoclopramide: increased risk of extrapyramidal side-effects when antipsychotics given with metoclopramide.
Moxonidine: enhanced hypotensive effect when phenothiazines given with moxonidine.
Nitrates: enhanced hypotensive effect when phenothiazines given with nitrates.
Pentamidine Isetionate: increased risk of ventricular arrhythmias when phenothiazines given with pentamidine isetionate.
Sibutramine: increased risk of CNS toxicity when antipsychotics given with sibutramine (manufacturer of sibutramine advises avoid concomitant use).
Sodium Oxybate: antipsychotics possibly enhance effects of sodium oxybate.
Sympathomimetics: antipsychotics antagonise hypertensive effect of sympathomimetics.
Tetrabenazine: increased risk of extrapyramidal sideeffects when antipsychotics given with tetrabenazine.
Ulcer-healing Drugs: effects of antipsychotics, chlorpromazine and clozapine possibly enhanced by cimetidine.
Vasodilator Antihypertensives: enhanced hypotensive effect when phenothiazines given with hydralazine, minoxidil or sodium nitroprusside.
When phenothiazines given with tricyclic antidepressants, maprotiline or monoamine oxidase (MAO) inhibitors the risk of neuroleptic malignant syndrome (NMS) may be increased.