DDIs: Additive Effects

Question 1

Serotonin Syndrome Symptoms

Answer 1

• sweating
• N/V
• fever
• AMS
• rigidity / tremor
• seizure

Question 2

Drugs with additive risk for hyperkalemia

Answer 2

• RAAS drugs
• Potassium sparing diuretics (Amiloride, triamterene)
• Salt substitutes (KCl)
• Calcineurin inhibitors (tacrolimus, cyclosporine)
• SMX/TMP
• canagliflozin
• drospirenone containing contraceptives

Question 3

Hyperkalemia symptoms

Answer 3

• weakness
• palpitations
• arrhythmia

Note: higher risk with renal impairment

Question 4

QT prolonging anti-infectives

Answer 4

• hydroxychloroquine
• azole antifungals
• lefamlin
• macrolides
• quinolones

Question 5

QT prolonging antidepressants

Answer 5

• escitalopram & citalopram
• TCAs
• mirtazapime
• trazodone
• venlafaxine

Question 6

QT prolonging antipsychotics

Answer 6

• First gen (haloperidol, thioridazine)
• Second gen (highest risk with ziprasidone)

Question 7

QT prolonging Antiemetics

Answer 7

• ondansetron
• droperidol
• metoclopramide
• promethazine

Question 8

QT prolonging oncology medications

Answer 8

• leuprolide
• nilotinib
• oxaliplatin

Question 9

Misc QT prolonging agents

Answer 9

• cilostazol
• donepezil
• fingolimod
• hydroxyzine
• loperamide
• ranolazine
• solifenacin
• methadone
• tacrolimus

Question 10

QT prolongation precaution: Citalopram dosing in pts > 60

Answer 10

max 40mg daily

Question 11

QT prolongation precaution: Escitalopram dosing in pts > 60

Answer 11

Max 20mg daily

Question 12

Drugs with additive ototoxicity

Answer 12

• Aminoglycosides (gentamicin, tobramycin, amikacin)
• Cisplatin
• Loop diuretics (furosemide, bumetanide)
• Aspirin
• Vancomycin

Question 13

Drugs with additive nephrotoxicity

Answer 13

• Anti-infectives (aminoglycosides, amphotericin B, polymyxins, vancomycin)
• Cisplatin
• Calcineurin inhibitors (tacrolymus, cyclosporine)
• Loop diuretics
• NSAIDs
• Contrast dye

Question 14

Drugs with additive hypotensive effects

Answer 14

PDE-5 inhibitors (sildenafil, tadalafil)
+
CYP3A4 inhibitors
OR
Nitrates
OR
Alpha 1 blockers (doxazosin, terazosin, tamsulosin)