# Review the dofetilide initiation record and determine the correct dose decision.

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> url: https://mymerci.kr/pages/nclex_q.php?qn_id=514124&lang=en  
> language: en  
> subject: Adverse Effects/Contraindications/Interactions  
> category: PPT

## Question

Review the dofetilide initiation record and determine the correct dose decision.

| Time | Data |
| --- | --- |
| Baseline | 68-year-old woman; 70 kg; serum creatinine 1.3 mg/dL; QTc 430 msec; potassium 4.2 mEq/L; magnesium normal |
| Calculation | Female Cockcroft-Gault creatinine clearance approximately 46 mL/min |
| Dose 1 | Dofetilide 250 mcg administered; continuous ECG monitoring in place |
| 3 hours after Dose 1 | QTc 470 msec; 250-mcg regimen continued according to the authorized protocol |
| 3 hours after Dose 2 | QTc 512 msec; client denies symptoms |

Q1. Was the original 250-mcg dose consistent with the renal calculation?

Yes
No

Q2. What is the priority response to QTc 512 msec after Dose 2?

Give the next dose early because the client has no symptoms
Continue unchanged and repeat QTc after discharge
Discontinue dofetilide per protocol and notify the authorized clinician

## Explanation

The female Cockcroft-Gault clearance is approximately 45 mL/min, which supports 250 mcg BID. A post-dose QTc above 500 msec requires discontinuation rather than another dose.

## In-depth explanation

Quick answer
The starting dose matches the renal band, but the later QTc requires discontinuing dofetilide and notifying the authorized clinician.

Why this is correct
For a woman, Cockcroft-Gault includes the 0.85 factor: (140-68) times 70 divided by (72 times 1.3), then times 0.85, or about 46 mL/min. The 40-to-60 band uses 250 mcg BID. After a subsequent dose, QTc greater than 500 msec requires discontinuation.

Easy analogy or mental picture
The renal calculation chooses the starting lane; the QT monitor can still close the road.

Memory hook
CrCl sets the first dose; QTc decides whether the trip continues.

NCLEX decision rule
Use the labeled sequence: baseline QT, calculated clearance, renal dose, continuous ECG, and post-dose QT checks.

Why the other choices are wrong
A correct starting dose does not authorize continued therapy after a stop-threshold QTc.References
1DailyMed: Dofetilide CapsulesSex-specific Cockcroft-Gault calculation, renal starting dose, and post-dose QTc monitoring

## Clinical scenario

Dofetilide initiation
Verify baseline QTc, sex-specific Cockcroft-Gault clearance, potassium and magnesium, dose band, telemetry, and QTc 2 to 3 hours after doses.

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