WHAT IS OPIOID SUBSTITUTION THERAPY MEDICINES?

OPIOID SUBSTITUTION THERAPY MEDICINES
The medicines used in OST should have certain properties that help the clients obtain the benefits discussed above. The OST medicine should:

•  Have action similar to the illicit opioid used by the clients. This is essential to effectively suppress the craving and withdrawals associated with cessation of opioid use. This means that an OST medicine should also be an agonist on the OPIOID receptors.

•  Have lesser addiction potential as compared to the illicit opioid being consumed by the client. Any OST medicine will have some liability to result in addiction, as it is an opioid. However, its street value should be much less than the illicit opioids, i.e. users should not prefer the OST medicine over illicit opioids for their addiction/intoxication.

•  Be easy to administer i.e. the medicine should be effective on oral or sublingual administration.

• Have action lasting for at least 24 hours, so that the frequency of administration should be once a day at the maximum.

•  Be well tolerated. The side effects should be minimal so that the clients find it acceptable to continue OST medicines for a long period of time

•  Be cheaper, easily available, easily stored and transported, so as to provide for a large number of clients with minimal financial or logistic constraints.

In India, methadone, buprenorphine and slow release oral morphine have been used as OST medicine. However, the use of buprenorphine exceeds that of the other two; OST programme under NACP currently uses buprenorphine as the OST medicine, and hence buprenorphine has been discussed in detail in subsequent sections. Methadone based OST is also being implemented as a pilot at five sites in India.

PHARMACEUTICAL COMPOUNDS COMMONLY USED AS OST MEDICINES

1. Methadone: Methadone was the first and currently, the most common opioid used as an OST medicine globally. Methadone is a pure opioid agonist, available for oral use either as a liquid or as a tablet.
2.  Buprenorphine: Buprenorphine is a partial opioid agonist available for use as a sublingual tablet. It is the second most commonly used OST medicine worldwide.
3.  Slow Release Oral Morphine: Morphine is a pure opioid agonist and commonly used in cancer patients for alleviation of pain. The slow release formulation is available as a tablet.