will not lower your heart rate
. However, some over-the-counter cough
remedies containing other substances in addition to ibuprofen might. It would be difficult to predict the response to these medications.
There are better medications and psychological techniques to reduce your heart rate.
You also need to address
1. Why your heart rate is over 100/min
2. The reason and adverse effects of your clinical obesity (BMI 35.5)
3. The reasons for donating plasma twice a week
I would suggest you seek professional psychiatric help. It would help resolve all these issues.