Stability and Sterility of Parenteral Solutions – A Short Case

Posted by Dr Dan Carter

A prospective patient called my office and inquired about intramuscular vitamin B12 injections. She stated that she had undergone an ileectomy and required B12 injections since that time. She had heard from a friend that methylcobalamin may be more beneficial for her than the “regular kind” she was using. After a rather pointed question and answer period I found that her “regular kind” was cyanocobalamin, 30 mL vial, 1000 micrograms per mL and she was injecting 2 mL once a month. She stated that the vial was stored at room temperature and was used until gone, which typically took over a year. She admitted that effectiveness seemed less when the vial was getting empty, but said that no infection occurred at injection sites.

There were two important issues the patient brought up: how long can a multi-dose vial maintain sterility after multiple entries, and what happens to drug potency after prolonged exposure to variable room temperature and air? Sterility is the main safety issue and prevention of iatrogenic infection is a primary objective of any physician.

The current practice guideline for multiple dose vials is that they may be used for one month after first entry. Storage recommendations depend on what type of drug is involved. Cyanocobalamin is usually stored at room temperature, whereas other B-vitamins, methyl and hydroxo cobalamins, and minerals are normally stored in the refrigerator after first entry.

What is the best procedure to prevent infection when using parenteral drugs? Every check on the following list needs to be followed with every use of the drug. Note: this list covers correct drug use only. It does not address administration.

  1. Confirm the drug name
  2. Check the expiration date
  3. Check for clarity if the drug is a solution. Suspensions may be cloudy. Examine for precipitates
  4. Clean the top of the vial well with IPA or other approved antiseptic
  5. Enter the vial with a new sterile needle attached to an unused sterile syringe, introduce a volume of air that matches the drug volume and withdraw the drug
  6. Store appropriately

Another method to decrease contamination of frequently used vials is to use a needleless vial adapter. Vial adapters are inserted into a vial once, and stay in place until the vial is empty or it outdates. Air does not need to be pushed into the vial because the adapter has a filter that allows air entry as the drug is withdrawn. Here are two different brands:

This one is a Codan C350N vial adapter with Swan Lock needless entry.

And here is a B Braun Ultrasite adapter

 

I ordered her some methylcoblamin and instructed her in its proper and safe application.

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