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