Psychopharmacology

Question 1

Lithium interactions

Answer 1

Lithium Interactions:
Li level INCREASES with : –thiazide diuretics (hydrochlorothiazide),
-ACE inhibitors (captopril, enalapril),
-angiotensin II R antagonists (valsartan, losartan),
-NSAIDs (except ASA), COX-2 inhibitors (celecoxib etc)
-metronidazole, tetracycline, spectinomycin
LI level DECREASE with:
-Aminophylline, theophylline
-Urinary alkalization (acetazolamide, sodium bicarbonate)
-Sodium chloride (salt)
-Osmotic diuretics (mannitol)

Question 2

MAO inhibiter interactions

Answer 2

MAO Inhibitor Interactions
• Hypertensive Crisis
○ With sympathomimetics
§ OTCs: pseudoephedrine, phenylephrine, oxymetazoline
§ Inhibition of MAO-A primarily
□ Less risk with selegiline patch <6mg/24h (as mostly MAO-B)– but at higher doses non-specific for MAO-A and MAO-B
–>Serotonin syndrome

Question 3

MAOi inhibitor interactions

Answer 3

• Serotonin Syndrome
• Develops over hours– usually no unique lab findings
○ Narcotics: meperidine (demerol) especially, with codeine and morphine- generally safer although use with caution
○ Serotonergic agents
§ SSRIs and MAOi’s are ABSOLUTELY Contraindicated
§ Wait 5 weeks after fluoxetine before MAOi and, 4-5 t1/2 after other SSRI or other serotonergic agents
§ Wait 2 weeks after MAOis before starting SSRI or other serotonergic agent to allow MAO to regenerate
§ Antidepressants: SSRI, SNRI, other MAOi’s, nefazodone, mirtazapine, buspirone
§ Lithium
§ St John’s Wort
§ carbamazapine
§ L-tryptophan
§ Dextromethorphan
§ Sumatriptin

Question 4

Hunter Criteria for Serotonin Syndrome

Answer 4

○ Hunter Criteria for Serotonin Syndrome
ANY OF THE FOLLOWING SETS (A-E)
(A) Spontaneous clonus
(B) Inducible clonus plus agitation or diaphoresis
(C) Ocular clonus plus agitation or diaphoresis
(D) Tremor plus hyperreflexia
(E) Hypertonicity plus fever plus ocular clonus or inducible clonus

Question 5

CYP 1A2

Answer 5

Substrates: clozapine, olanzapine, haldol, fluvoxamine, duloxetine, imipramine
Inhibitors (increase levels): fluvoxamine, fluoroquinolones, cimetidine
Inducers (decrease levels): carbamazepine, tobacco, rifampin

Question 6

CYP 2C19

Answer 6

Substrate: citalopram, amitryptyline, imipramine PPIs (lansoprazole etc), anti epileptics (diazepam, phenytoin, phenobarbitals),
Inhibitors (increase levels): fluoxetine, fluvoxamine, PPIs, contraceptives
Inducers (decrease levels): St John’s wort, rifampin, ritonovir (ARV)

Question 7

CYP 2D6

Answer 7

Substrate: fluoxetine, paroxetine, duloxetine, TCAs (amitryptyline, clomipramine, despiramine, imipramine), haldol, risperidone, aripiprazole, atomoxetine, codeine, dextromethorphan, ondansetron
Inhibitor (increase levels): bupropion, fluoxetine, paroxetine, quinidine, duloxetine, aripiprazole, haldol
Inducer (decrease levels): none

Question 8

CYP 3A4, 5, 7

Answer 8

Substrate: levomilanacipran, vilazodone, quetiapine, lurasidone, haldol, methadone, benzos (alprazolam, diazepam, midazolam, triazolam), macrolide antibiotics (clarithromycin etc- not azithromycin), immune modulators (cyclosporine, tacrolimus, sirolimus), HIV antiretrovirals (-avir)
Inhibitors (increase levels): fluvoxamine, suboxone, HIV antiretrovirals (-avir), macrolide abx, grapefruit juice, antifungals (-azole)
Inducers (decrease levels): carbamazepine, St Johns Wort, phenobarbitals, phenytoin, rifampin

Question 9

antipsychotics and QTc prolongation

Answer 9

QTc most prolonged (in decreasing order): Thorazine, ziprasidone, risperidone, olanzapine, quetiapine, haloperidol
o Not known to prolong QTc: lurasidone, aripiprazole, paliperidone, asenapine

Question 10

antidepressants and QTc prolongation

Answer 10

SSRI without QTc prolongation: fluoxetine, fluvoxamine, sertraline, paroxetine
Increased QTc with buproprion, citalopram and amitryptline

Question 11

antidepressants and sexual side effects

Answer 11

CANMAT Depression 2016 agents with less sexual side effects incl: agomelatine, buproprion, mirtazapine, vilazodone, vortioxetine