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There
has been increasing interest in the shelf life of methadone hydrochloride
products once OTP personnel have mixed the medication and dispensed
it in take-home dosages. This interest has increased following the
publication of CSAT's accreditation regulations, which provides
greater clinical flexibility in prescribing take-home medications.
The
manufacturers of methadone hydrochloride products are not able to
provide any guidance with regard to the shelf life of their products
once the seal of the original container has been broken and OTP
personnel have added other ingredients to the original pharmaceutical
product.
According
to an article, as authored by Lloyd Allen and M. Lou Stiles (U.S.
Pharmacist - September 1988) "Methadone is a relatively stable
drug and the potential problem is not necessarily with the methadone
but with the vehicle which might become contaminated with mold or
fungal growth".
Some
programs dispense take-home medication with tap water while others
dispense such medication with various flavored products. Another
article authored by G. Lauriault et al. "Stability of Methadone
in Four Vehicles for Oral Administration" appeared in the American
Society of Hospital Pharmacists (1991). The following results were
reported: "Methadone was stable (loss of potency, < 5 %)
for up to seventeen, eleven, nine and eight days when stored at
20-25 degrees C in Kool-Aid, Tang, apple juice and Crystal Lite,
respectively, and for up to 29 days when stored at 20-25 degrees
C in Crystal Lite plus sodium benzoate".1
After
a review of the existing but limited literature on the topic and
discussions with a number of pharmacists, there appears to be a
consensus around three particular points.
1. It is recommended that the methadone hydrochloride products
be dispersed using distilled water only.
2.
It is recommended that the methadone hydrochloride products be
dispensed in clean, new, air tight, light resistant containers.
3.
It is recommended that the methadone hydrochloride products be
securely refrigerated as soon as possible and remain refrigerated
until time of use.
If these recommended procedures are followed, methadone hydrochloride
products should remain stable for up to a thirty-day period of time
from date of OTP dispensing.
1
Sodium benzoate is a recognized pharmaceutical preservative
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