Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel Blockers

Question 1

Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel Blockers
Drug Names

Answer 1

Ivabradine

Question 2

Therapeutic Actions and Indications

Answer 2

Blocking the HCNs slows the heart’s pacemaker, the sinus node, in the repolarization phase of the action potential

Question 3

Contraindications and Cautions

Answer 3

Known allergies
Active, decompensated HF; hypotension; sick sinus syndrome of AV block; resting heart rate under 60bpm; patients completely dependent on pacemaker and severe hepatic impairment
Caution: atrial fibrillation or moderate heart block

Question 4

Adverse Effects

Answer 4

Bradycardia, hypertension, atrial fibrillation, and luminous phenomena (sudden changes in brightness in parts of the visual field, colored bright lights, image decompensation, multiple images)

Question 5

Drug-Drug Interactions

Answer 5

CYP3A4 inhibitors or inducers

Negative chronotropic drugs

Question 6

Assessment

Answer 6

HX & Physical: known allergy; AV block, decompensated HF, dependence on a pacemaker, resting heart rate under 60bpm, hypotension; severe hepatic impairment or concurrent use of CYP3A4 inhibitors; cardiac status, ECG and appropriate lab values