Pharmacist’s Corner: Controlled Substance Cycle Counts

Jun 8, 2021 / Practitioner Updates

Hopefully controlled substance inven­tory is part of your annual inventory procedures. However, if controlled substance counts are only verified once a year, if something is missing, a year is a lot of records to sort through trying to identify where the drug went missing. Therefore, it is recommended to do more frequent inventory.

I suggest either a weekly or monthly physical count of controlled substanc­es, if possible. This small but frequent time investment can save a lot of headaches later.

Cycle counts can be done by anyone designated by the DEA license holder. Generally, a cycle count involves:

  1. Verifying the quantity of a drug on hand
  2. Comparing this quantity to the amount that is expected, based on running inventory logs 2a. If quantities match, make a note in the log and move to the next drug. 2b. If quantities don’t match, verify your count and then investigate why the quantities don’t match.

Possible discrepancy causes to consid­er if you have more than expected:

  • Manufacture overfill: A vial of an injectable drug can contain up to 10% more than stated to account for hub loss and drug that can’t be removed. Therefore, a 10-ml vial may actually have close to 11 ml of drug.
  • A dose being logged but not re­moved
  • A dose being logged twice but only removed once

Possible discrepancy causes to consid­er if you have less than expected:

  • Hub loss: Standard hub loss is considered to be 0.05 ml/stick. To determine if the loss is attributable to hub loss, multiply the number of sticks since last check by 0.05ml. This is the acceptable hub loss.
  • Leaky vials: When vials are poked several times, the cork can lose its integrity. In these cases, you can see drug dripping out of the vial while drawing up a dose. Leaking should be marked on the log.
  • Inaccurate draws/logging: Make sure that everyone is trained on correctly reading a syringe.
  • Dose not logged

This month’s column is from Lauren Forsythe, PharmD, FSVHP.