VP is your patient in the cardiac care unit (CCU) when she becomes tachycardic. The patient is not hypotensive, showing signs of shock, altered mental status, or with ischemic discomfort. The patient has a narrow QRS of 0.6 with the EKG showing paroxysmal supraventricular tachycardia. This patient is currently being monitored in the CCU after having a coronary artery bypass graft (CABG) surgery. The team decides to use adenosine to slow the patient’s heart rate and correct the paroxysmal supraventricular tachycardia after already trying vagal maneuvers. 

PMH: Coronary Artery Disease, Hypertension, T2DM, HIV

Current Medications: Coreg 25 mg BID, Lisinopril 20 mg daily, Lipitor 80 mg daily, ASA 81 mg daily, Metformin 1000 mg BID, Biktarvy one tablet daily

Vitals: 
HR: 150 bpm BP: 120/80 mmHg

EKG: Paroxysmal Supraventricular Tachycardia

Which of the following are correct regarding adenosine? Select all that apply:

A. Adenosine is initially dosed 12 mg IV rapid push x 1 followed by saline flush and if no resolution occurs within 1-2 minutes another dose of 6 mg IV rapid push may be administered.
B. Adenosine can cause bradycardia and facial flushing after administration. 
C. Adenosine is initially dosed 6 mg IV rapid IV push x 1 followed by saline flush. If no resolution occurs within 1-2 minutes, another dose of 2 mg IV rapid push may be administered.
D. Adenosine is contraindicated in patients with second or third degree AV block.
E. Adenosine should not be administered if the patient recently took their dose of Coreg. 

Rationale: 
Knowing the doses of common agents used in the advanced cardiovascular life support (ACLS) algorithm is incredibly important for pharmacists, but it is also important to know what to expect with these drugs and when they are contraindicated. If working in a hospital pharmacy including staffing, codes can happen at any time and pharmacists are often involved with drug therapy preparation and distribution to nursing for administration. Particularly for adenosine, it carries a risk of AV block and knowing other agents that can increase the risk for AV block is important. A pharmacist should also know the typical side effects after administration of adenosine to prepare the team and patient. 

Dosage and Administration: Adenosine requires rapid IV bolus administration in order for it to work before it is rapidly metabolized. This is because it has a half life of 10 seconds in whole blood. Dosage is also important, because adenosine is first administered as 6 mg IV rapid push with a saline flush after and can be followed by 12 mg IV rapid push if no resolution occurs in 1-2 minutes (Both Answers A and C are therefore incorrect due to wrong doses listed).  

Adverse Effect Profile: After the adenosine has been administered it is common for patients to be bradycardic and experience facial flushing and headache (Answer B is correct).  As a bonus, patients should be counseled that the EKG will appear as a flat line looking like asystole for a few seconds indicating the drug is working. 

Contraindications: Adenosine is contraindicated in patients with AV block, because it works by slowing conduction through the AV node (Answer D is correct). Additionally patients who develop high-level AV block after one dose of adenosine shouldn't get any more doses. It is also contraindicated in sinus node disease. 

Drug Interactions: Adenosine is not contraindicated with beta blockers, ACE inhibitors, or calcium channel blockers and should still be used in the presence of these agents (Answer E is incorrect). Caution should however be used in the presence of digoxin and verapamil due to the potential for additive or synergistic depressant effects on the SA and AV nodes. Larger doses of adenosine may be required following recent caffeine or theophylline use due to antagonistic effects of both agents. Another interaction of note is the potential increase in AV heart block when adenosine is used in the presence of carbamazepine. 

Correct Answers: B and D

Generics/Brands Covered: Adenosine (Adenocard), Carvedilol (Coreg), Lisinopril (Zestril), Atorvastatin (Lipitor), Metformin (Glucophage), Bictegravir, Emtricitabine, and Tenofovir Alafenamide (Biktarvy)

NAPLEX Core Competencies covered:
2.1(mechanism of action), 3.4 (Drug dosing or dosing adjustments), 3.5(Drug route of administration), 3.6(Drug contraindications), 3.7(Adverse drug effects), 3.8(Drug interactions), 

Sources: 
https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/019937s026lbl.pdf

https://cpr.heart.org/-/media/cpr-files/cpr-guidelines-files/algorithms/algorithmacls_tachycardia_200612.pdf