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Showing posts with label Drug Interactions. Show all posts
Showing posts with label Drug Interactions. Show all posts
Drug interactions with anxiolytics and hypnotics (Table 8.14L)
By Piscean | Monday, January 9, 2012 | Posted in , , , | With 0 comments


Drug interactions with anxiolytics and hypnotics (Table 8.14L)
Anxiolytics include benzodiazepines and buspirone. Hypnotics include benzodiazepines, zolpidem and zopiclone.
Drug
Rating [NB1]
Interaction
Recommended action
Analgesics, opioid (including tramadol)
2
Respiratory depression with benzodiazepines, especially if given parenterally.
Monitor for respiratory depression.
Antiretrovirals: ritonavir, saquinavir
3
Increase plasma concentration of alprazolam, buspirone and triazolam (CYP3A4 inhibition).
Monitor for adverse effects.
Consider use of an alternative anxiolytic or hypnotic, eg lorazepam, oxazepam or temazepam.
Azole antifungals: fluconazole, itraconazole, ketoconazole
2
May increase plasma concentrations of alprazolam, triazolam, buspirone, zolpidem and zopiclone (CYP3A4 inhibition).
Monitor for adverse effects. Use an alternative benzodiazepine or alternative antifungal drug, eg terbinafine.
Calcium channel blockers
3
Diltiazem and verapamil may increase plasma concentrations of buspirone and triazolam (CYP3A4 inhibition).
Monitor for adverse effects. Use an alternative calcium channel blocker or alternative anxiolytic, eg lorazepam, oxazepam or temazepam.
Cimetidine
3
Increases plasma concentrations of alprazolam, diazepam, nitrazepam and triazolam (CYP3A4 inhibition).
Monitor for adverse effects. Use an alternative H2-receptor blocker or alternative benzodiazepine, eg lorazepam, oxazepam or temazepam.
Clarithromycin -
Disulfiram
3
Decreases diazepam metabolism.
Monitor for adverse effects. Use an alternative drug, eg alprazolam, oxazepam or lorazepam.
ECT
2
Benzodiazepines raise seizure threshold, which may impair the efficacy of the ECT.
Taper and cease benzodiazepines before ECT.
Erythromycin -
Esomeprazole -
Macrolide antibiotics: clarithromycin, erythromycin
2
Increase plasma concentrations of alprazolam, triazolam, buspirone, and zopiclone (CYP3A4 inhibition).
Monitor for adverse effects. Use an alternative antibiotic, eg roxithromycin, or alternative anxiolytic, eg lorazepam, oxazepam or temazepam.
MAOIs, irreversible nonselective
3
Hypertension reported rarely with buspirone.
Monitor for increased blood pressure or use an alternative drug.
Nefazodone -
Omeprazole -
Proton pump inhibitors: esomeprazole, omeprazole
3
Decreased clearance of diazepam reported (possibly inhibition of CYP3A, CYP2C9 or CYP2C19).
Monitor for adverse effects of diazepam or use alternative benzodiazepine or alternative proton pump inhibitor, eg rabeprazole
Rifabutin, rifampicin
3
Increased buspirone, diazepam, nitrazepam, triazolam, zolpidem and zopiclone metabolism. Temazepam not affected.
Monitor for decreased effect of anxiolytic or hypnotic.
Ritonavir -
Saquinavir -
SSRIs and nefazodone
2
Nefazodone inhibits metabolism (CYP3A4) of alprazolam, triazolam and zopiclone. Fluoxetine and fluvoxamine increase plasma alprazolam and diazepam concentrations. Unlikely with paroxetine or sertraline.
Monitor for benzodiazepine adverse effects or use alternative anxiolytic, eg lorazepam, oxazepam or temazepam.
3
Several reports of adverse effects with fluoxetine and buspirone.
Monitor for increased adverse effects such as worsening of psychiatric symptoms, serotonergic effects or seizure with buspirone and fluoxetine.
Tramadol -
NB1:
Rating 1 – Avoid combination; risk always outweighs benefit.
Rating 2 – Usually avoid combination; use combination only under special circumstances.
Rating 3 – Minimise risk; take action as necessary to reduce risk.

Drug interactions with antidepressants: TCAs (Table 8.14F)
By Piscean | Thursday, September 29, 2011 | Posted in , , , , , | With 0 comments

Drug interactions with antidepressants: TCAs (Table 8.14F)
TCAs include amitriptyline, clomipramine, dothiepin, doxepin, imipramine, nortriptyline and trimipramine.
Drug
Rating [NB1]
Interaction
Recommended action
Antipsychotics, typical
3
Plasma concentrations of both the antipsychotic and the TCA may increase. Additive adverse effects also possible.
Monitor for adverse effects.
Barbiturates
3
TCA metabolism increased.
Use with caution.
Carbamazepine
3
Variable effect on plasma TCA concentrations, ie amitriptyline, imipramine and nortriptyline decreased and clomipramine increased.
Unresponsive patients may need higher doses of TCAs. Observe for carbamazepine or clomipramine toxicity.
Cimetidine
3
TCA metabolism inhibited by cimetidine.
Use an alternative H2-receptor antagonist.
Clonidine
2
TCAs may reduce clonidine’s antihypertensive effect. On clonidine cessation, TCAs may worsen rebound hypertension.
Avoid combination.
Dextropropoxyphene
3
Doubles plasma doxepin concentration and adverse effects increased.
Use an alternative analgesic.
Fluconazole
2
Fluconazole increases amitriptyline and nortriptyline plasma levels, probably due to inhibition of CYP2C9 and CYP3A4 metabolism.
Avoid combination of TCA and fluconazole or monitor for TCA adverse effects.
MAOIs, irreversible nonselective
1
Serotonin syndrome and fatalities reported.
Avoid combination of MAOI and TCA. Care needed in changing between MAOI and TCA, especially clomipramine, 
Moclobemide
2
Serotonin syndrome reported with clomipramine and possible with other serotonergic TCAs.
Avoid combination of moclobemide and TCA. Care needed in changing between moclobemide and TCA, especially clomipramine,
Nefazodone - 
NSAIDs
3
Increased risk of upper gastrointestinal tract bleeding when clomipramine and NSAID are coadministered. Patients with a history of peptic ulcer or oesophageal varices at most risk.
Monitor for evidence of gastrointestinal tract bleeding or use alternative analgesic or alternative antidepressant with minimal serotonergic effect.
Quinidine
2
Reduces TCA metabolism probably due to CYP2D6 inhibition.
Use alternative antidepressant.
SSRIs and nefazodone
2
Plasma TCA concentrations increased, especially with fluoxetine, fluvoxamine and paroxetine. Serotonin syndrome also possible especially with clomipramine.
Avoid combination of TCA and SSRI or nefazodone, except under specialist supervision. The interaction may vary with different SSRIs and may be less likely to occur with citalopram. Care needed in changing between TCA and SSRI or nefazodone, see Table 8.11.
Sympathomimetic amines, parenteral--directly acting: adrenaline, dopamine, isoprenaline, noradrenaline
2
Grossly exaggerated pressor response to adrenaline, phenylephrine and noradrenaline. Does not occur with indirectly acting sympathomimetics, eg isoprenaline or felypressin. Some reports of adrenergic effects, eg headache, dilated pupils, increased blood pressure with dental local anaesthetics (lignocaine with noradrenaline).
Avoid combination of TCA and parenteral sympathomimetics or use with great caution in patients taking TCAs. In anaphylaxis, benefit may outweigh risk.
Venlafaxine
2
Venlafaxine may increase plasma imipramine, clomipramine and nortriptyline concentration due to CYP2D6 inhibition.
Avoid combination of venlafaxine and imipramine, clomipramine or nortriptyline. Care needed in changing between venlafaxine and TCA, see Table 8.11.
NB1:
Rating 1 – Avoid combination; risk always outweighs benefit.
Rating 2 – Usually avoid combination; use combination only under special circumstances.
Rating 3 – Minimise risk; take action as necessary to reduce risk.
Drug interactions with antidepressants: irreversible nonselective MAOIs
By Piscean | | Posted in , , , , , | With 0 comments
Drug interactions with antidepressants: irreversible nonselective MAOIs 
Irreversible nonselective MAOIs include phenelzine and tranylcypromine.
Drug
Rating [NB1]
Interaction
Recommended action
Alcohol
2 or 3
Tyramine reaction (see under tyramine) possible with some alcoholic beverages.
See irreversible nonselective MAOI dietary guidelines, Table 8.3.
Analgesics, opioid (including tramadol)
1
Excitation, sweating, rigidity and hypertension; or hypotension and coma with pethidine.
Pentazocine may also be risky.
Case reports of serotonin syndrome occurring with tramadol and MAOI.
Avoid combination of pethidine and MAOIs (absolute contraindication). Morphine may be used judiciously; titrate small IV doses, and have naloxone and noradrenaline (as a vasopressor) available.
Avoid tramadol in patients who are taking MAOIs or who have taken them in the last 14 days.
NSAIDs or paracetamol/codeine combinations may be suitable alternatives.
Buspirone
3
Hypertension reported rarely.
Monitor for increased blood pressure or use an alternative drug.
Clomipramine - 
Dexamphetamine - 
Dextromethorphan
2
A case of nausea, hypotension, fever and coma after low doses of dextromethorphan; dizziness, muscle tremor and urinary retention in another case.
Avoid dextromethorphan with MAOI. Use an alternative antitussive, eg pholcodine.
ECT
3
No interaction, but see also, entry for suxamethonium in this table.
Two-week gap not needed; stop MAOI and start ECT when pre-ECT work-up is done.
Hypoglycaemics, including insulin
3
Enhanced hypoglycaemic response to insulin and oral hypoglycaemics.
Use alternative antidepressant if possible.
Levodopa
1
Severe hypertensive reactions reported.
Avoid combination of MAOI and levodopa.
Linezolid
2
Manufacturer warns to be alert for increased risk of hypertensive crisis with linezolid and MAOI.
Avoid combination of MAOI and linezolid. Use an alternative antidepressant.
MAOIs, irreversible nonselective
1
Rare fatalities reported when changing from 1 irreversible nonselective MAOI to another.
Cease first MAOI, wait 14 days, and start with small doses of new MAOI, see Table 8.11.
Methylphenidate - 
Mianserin and mirtazapine
1
Manufacturer of mirtazapine recommends avoiding concurrent use.
Avoid combination of MAOI and mianserin or mirtazapine. Care needed in changing between MAOI and mianserin or mirtazapine, 
Moclobemide
1
Serotonin syndrome possible.
Avoid combination of MAOI and moclobemide. Care needed in changing between MAOI and moclobemide,
Modafinil
2
Manufacturer recommends caution when administering MAOI with modafinil.
Avoid combination of MAOI and modafinil.
Naratriptan -
Nefazodone - 
Pentazocine - 
Pethidine - 
Psychostimulants: dexamphetamine, methylphenidate -
Reboxetine
1
Manufacturer recommends avoiding concurrent use.
Avoid combination of MAOI and reboxetine. Care needed in changing between MAOI and reboxetine, 
Serotonergic agonists: SSRIs, clomipramine, nefazodone, sibutramine, tryptophan, venlafaxine
1
Serotonin syndrome possible. Fatalities reported with fluoxetine and MAOI combination.
Avoid combination of MAOI and serotonergic agonist.
Care needed in changing between serotonergic antidepressant and MAOI,
Sibutramine - 
SSRIs and nefazodone - 
Sumatriptan - 
Suxamethonium
3
Phenelzine prolongs muscle relaxation by inhibiting metabolism.
Decrease suxamethonium dose and monitor carefully or use pancuronium.
Sympathomimetic amines—directly acting: adrenaline, dopamine, isoprenaline, noradrenaline
3
Directly acting amines like the endogenous transmitters are inactivated principally by catechol-O-methyltransferase, not MAO.
No interaction or only a slight increase in blood pressure. Use cautiously and monitor.
Sympathomimetic amines—indirectly acting (often found in cough and cold remedies): amphetamines, diethylpropion, ephedrine, methylphenidate, phentermine, phenylephrine, pseudoephedrine, tyramine
1
Indirectly acting sympathomimetics and MAOIs may cause severe hypertension, chest pain, severe occipital headache and tachycardia. Also reported are neck stiffness, limb hypertonicity, seizures, sweating, flushing, fever, vomiting, stroke and cardiac failure.
Avoid combination of MAOI and indirectly acting sympathomimetic (absolute contraindication).
TCAs
1
Serotonin syndrome and fatalities reported.
Avoid combination of MAOI and TCA. Care needed in changing between MAOI and TCA, especially clomipramine, 
Tramadol - 
Triptans: naratriptan, sumatriptan, zolmitriptan
2
Rare occurrence of serotonin syndrome is possible.
Monitor for serotonin syndrome.
Tryptophan - 
Tyramine and foodstuffs containing tyramine
1
Hypertensive crisis with tyramine or dopa in foods.
See treatment options for hypertensive emergencies.
Warn and give patient dietary guidelines,
Venlafaxine - 
Zolmitriptan -
NB1:
Rating 1 – Avoid combination; risk always outweighs benefit.
Rating 2 – Usually avoid combination; use combination only under special circumstances.
Rating 3 – Minimise risk; take action as necessary to reduce risk.