Tramadol hydrochloride (Tramake Insts / Zamadol / Zydol / Dromadol SR / Larapam SR / Zamadol 24hr / Zamadol SR / Zydol SR / Zydol XL) is an opioid drug that is used to treat moderate to severe pain. It is available in injectable forms and tablets. It is around 10% as potent as morphine.

In contrast to other opioid drugs, tramadol acts not only through the mu-opioid receptor, but also through affecting other brain chemicals, including gamma-amino butyric acid (GABA), noradrenaline and 5-hydroxytryptamine (serotonin).

Tramadol’s side-effects include nausea, vomiting and sweating, as well as mild drowsiness. Tramadol is unlikely to inhibit breathing or to cause dependence.

Tramadol may interact with protease inhibitors and the non-nucleoside reverse transcriptase inhibitor efavirenz (Sustiva). However, further research is required to establish how important these interactions may be.