Question: I’m sorry ahead of time for the long explanation.
My wife has Cyclic Vomiting Syndrome (CVS), diagnosed 18 years ago. In April, she had a port-a-catch installed due to her lack of viable veins. This has made the process so much less stressful and has allowed me to change from IM injections to IV. I have been diluting the promethazine 5:1 with .9% Sodium Chloride flush to prevent the drug from acting as battery acid on her main vein.
Currently she has been in the longest ongoing episode so far, lasting 36 days to date. So as you can imagine, it has been a struggle to keep up with my med stock.
My Dr has taken a vacation to Korea and I’m kind of stuck on my own right now. I’m running out of flush and with no refills, I’m ready to turn to the Heprin flush as an alternative dilute solution. My concern is that heprin being the blood thinner and promethazine having such a high PH, that the heprin might help the promethazine eat up her vein.
I tried using the drug interaction guides online, but apparently Heprin in not a drug and I can’t find out if there would be a problem.
Can you give me any guidance as to whether Heprin would be a suitable substitute to dilute the promethazine?

Thank you for your answer. Just so I'm clear on what I have. The script reads:
Heparin 500 Unit/5ML (100/ML) Qnty 100
I apparently misspelled it earlier.
The quantity of 100ml equals twenty 5 ml syringes of heparin.
So to clarify, the above as written needs to be diluted, or it is already diluted?
I am instructed to use it as is.
Thanks