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Dr. P. Jyoti
Dr. P. Jyoti, Consultant MD
Category: Medical
Satisfied Customers: 9126
Experience:  17 yrs experience in treating OPD & Emergency patients.
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My very active 75 year old sister-in-law was prescribed Profex

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My very active 75 year old sister-in-law was prescribed Profex 300 mg, to be carried on her person and be taken in case of rarely occuring tachycardia. She has these attacks once every several months to a year.
One morning in bed, she felt elevated heart rate and took the pill, and ended up blacking out and eventually in a hospital ER here in Israel. There were no further consequences to this event, and her cardiologist prescribed Tambocor 100 mg (Flecainide Acet.) as an alternative medication to be carried and used only in similar emergencies. Both medications warn of possible dizziness side effect, but neither warn of fainting (extreme blood pressure drop??).
Even my pharmacist seems to think that while there many medications in this field, there is no way to predict which might have a fainting side effect, and what dosage is optimal.
Cardiology is the exception to the Israeli rule that health care providers are quickly and easily available, so I'm turning to you to ask:
1. Is Tambocor optimal for such emergency one-time use?
2. Should she obtain a number of lower-dosage tablets, and take them one at a time, until her tachycardia subsides? If so, how fast acting would Tambocor (or alternative) be, and how long should she wait between the first tablet and subsequent tablets?
3. Are there further tests might she take to determine best treatment.
4. Is the tachycardia itself causing a sharp depression in blood pressure and therefore the cause of fainting, and we shouldn't be blaming the medication?

With regard to your questions,

Profex (Propafenone) would be the best for converstion of atrial fibrillation to normal rhythm.

There is no need to go for a number of low dose tablets. She should take the recommended dose as this will help her to convert to normal rhythm.

Discuss with her doctor about doing an Electrophysiological study. This is an important study for arrhythmia if not done already.

Yes, the fall in pressure is most likely due to the arrhythmia, the medication is not known to cause it.

Hope this shows you the way forward - wish her good health and a quick recovery.

I trust my answer has helped you gain more knowledge and confidence about your problem and in knowing what to discuss with your doctor.

I hope my answer has satisfied you. Please remember to rate my service once you have all the information you need. If you have any other questions, please ask me – I’ll be happy to respond. Bonus is always welcome - Thank you!

Dr.P.Jyoti, MD.
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Customer: replied 4 years ago.

The patient's cardiologist changed her prescription from Profex to Tambocor on the slight chance that she could be allergic to Profex, and that is was the allergic reaction that caused her fainting.

I learned today that she had another episode of tachycardia a couple of days ago and she avoided taking the Profex, thinking that she would also avoid the fainting... and after about an hour her heart rate returned to normal spontaneously. I warned her that her tachycardia could progress to arrythmia, and that could be lethal if she were alone and untreated.

This morning, she had another episode of tachycardia, and not yet having obtained the Tambocor, she took Profex. I was able to get to her about 90 minutes later and found her blood pressure 145/85, pulse 76, but she had a lingering headache and weakness. I'm a medical engineer and not an MD, but seem to fill in some of the blanks that her cardiologist misses (e.g. that increased pulse induces lowered blood pressure).

The cardiologist's report stated that if tachycardial episodes continue, he would recommend either taking amiodarone or performing ablation.


Any further comments on your part would be appreciated. Was my warning of tachycardia progressing into arrythmia correct? What might be behind her post-episode headaches and dizziness, despite normal blood pressure - could it be that my reading indicates at least temporary hypertension? Many thanks, Yehuda


Thats right, tachycardia can progress to full blown fibrillation which can be dangerous.

She should continue with the Profex, that is my considered opinion.

Initial use of any drug can lead to some side effects, these usually disappear with continued use.

The fainting during the initial episode was possibly due to low pressure as arrhythmias can lead to low pressure. I do not feel it is an allergic reaction since allergies would not cause fainting.

The headache is probably a side effect of the drug, it will stop occurring after continued use of the drug. But it is dangerous not to take the drug when she has tachycardia. The slight high pressure is not significant - probably due to her anxiety during the whole period.

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Customer: replied 4 years ago.

Dear Dr. Jyoti: I believe your advice was very sound. As a professional, I'd like to inform you of how the patient progressed. You may remember that initially she took Profex after not having trachycardia for a long time. The day of your last response, she had a further episode and was briefly hospitalized but tests did not indicate anything special. Then the episodes repeated on a daily basis, and after the fourth episode including continuing headaches and weakened strength, her cardiologist implanted a Medtronic ADDR01 Adapta DR Implantable Pulse Generator (IPG). A day later she was sent home to rest for a week, and she is now feeling quite well. The cardiologist apologized for not having picked up on the needed for pacing earlier.

hello Yehuda,

Very glad to hear that she is now safe and sound.

Nice to hear from you. Good that she has responded so well.

Remember to come back here if you have any other questions, I and other experts on the site are always ready to help you.

You can always request for me directly or begin your question with "for Dr. P. Jyoti", I will be very happy to be requested.