Does methadone spoil or go bad?
Since up to 30 days of methadone may be prescribed at one time in the U.S.
for take-home, there has been concern about the extended shelf life of liquid methadone.
Manufacturers can provide little guidance once the seal of the original container
is broken and methadone maintenance treatment (MMT) clinic staff add other ingredients
to the product.
Independent research and commentary confirms that methadone itself is a stable medication.
In one published report, pharmacists noted that potential problems relate more to
what is used to dilute the methadone at the time of dispensing, due to possible
contamination with mold or fungal growth.[1]
Bacterial growth also might be a concern. One investigation found that storage of
methadone mixtures at room temperature fostered visibly unacceptable bacterial growth
within 2 weeks, unless appropriate preservatives were included (such as, sodium
benzoate). As for potency, methadone mixed with Kool-Aid, Tang, apple juice, or
Crystal Light and refrigerated (41°F) maintained its strength for 30 days
or much longer.[2]
Based on a review of existing literature and a consensus of opinion among consulted
pharmacists, the American Association for the Treatment of Opioid Dependence (AATOD)
issued several recommendations in June 2004:[3]
- Dilution of methadone products should be with distilled
water only.
- New, clean, air tight, light resistant containers should
be used for dispensing.
- Take-home containers should be securely refrigerated as
soon as possible, and remain refrigerated until used.
AATOD specified that, if these procedures are followed, liquid methadone should
remain stable for up to 30 days from the date of MMT clinic dispensing.
However, there may be a question as to whether dilution at the time of clinic dispensing
is required or necessary. Federal Regulations do not specifically require dilution.[4]
Typically, product labeling specifies, “to be diluted with water or other liquid
to 30 mL (1 fluid oz.) or more before oral administration.”[5] This could mean dilution
“just before the dose is taken,” in which case the patient might be the one to add
liquid for dilution. Tap water or other fluid could be used, since storage is not
a concern. Dilution simply makes it easier to consume the full amount of otherwise
thick, undiluted methadone that is in the take-home container.
Sources:
1. Allen LV, Stiles ML. Methadone lemonade. U.S. Pharmacist. 1988(September):82.