Q: While administrating Procainamide, what is the cut off point to stop it depending on EKG criteria?
Answer: The QRS complex widens by 50% or more
Procainamide has a prolong action on cardiac muscles, particularly due to its metabolite N-acetylprocainamide (NAPA), which is also approximately equipotent with the parent drug as an antiarrhythmic agent. But to be of notice, NAPA has an elimination half-life about twice that of procainamide.
Procainamide should be discontinued when
- dysrhythmia is suppressed, or
- if hypotension ensues, or
- the QRS complex widens by 50% or more, or
- the maximum dose is achieved.