Medications to be Avoided
General principles and management of cancer pain in adults
Pethidine, meprobamate and caffeine are sometimes used for analgesia, either alone or in combination with other analgesics. They are not recommended for use in patients with cancer.
Pethidine (meperidine)
Pethidine is not suitable for the management of chronic pain. It has a faster onset of action and shorter duration of action than morphine, necessitating dosing every 2-3 hours. It is metabolised to norpethidine, which may have serious side effects, including mood changes, tremors, myoclonus and convulsions.16
Meprobamate
Meprobamate is a central nervous system depressant with anxiolytic, sedative and muscle relaxant properties. Side effects include confusion and loss of consciousness. It has a narrow therapeutic index with a steep dose-response curve, resulting in an increased risk of accidental overdose associated with serious and potentially fatal adverse events, including coma, profound hypotension, hypothermia, respiratory arrest and cardiogenic shock. When used for prolonged periods meprobamate carries a high risk of addiction, physical and psychological dependence. When discontinued abruptly, it is associated with severe, potentially fatal withdrawal symptoms. Consequently, the adverse effects associated with meprobamate outweigh its benefits and it should not be used.65
Caffeine
Caffeine is included in many combination analgesic products. When combined with non-opioid analgesics for the treatment of acute mild pain, it may be associated with a small increase in analgesic effect that is of questionable clinical relevance. Side effects, which include nervousness and dizziness, are common.66
Caffeine has no role in the management of cancer pain.