OPRM1 and COMT

OPRM1 and COMT appear to be promising genotypic markers for determining opioid sensitivity and the dose required for analgesic response. Given the recent institution of manda- tory ceilings on opioid prescription quantities and doses, insur- ers are now less likely to fill the appropriate opioid prescription for patients with severe cancer pain in the setting of these known polymorphisms. Although opioid dose selection and titration should be driven by patient-reported clinical response, these test results may offer an objective measurement to rein- force rapid or slow dose titration and improve clinical care.

Barb now has painful neuropathy from her chemotherapy,

so she is started on gabapentin by a nurse practitioner. Accord-

ing to her known pharmacogenomic profile, there is no altered

metabolism predicted based on her results, so the gabapentin is

escalated to 3,600 mg daily per usual practice. At full dose, there

is no perceivable benefit in her neuropathy, and she begins to

develop mental status changes, so you taper the gabapentin and

consider another medication. Barb’s insurance company states

that she must next try either nortriptyline or amitriptyline for

painful chemotherapy-induced neuropathy. If the tricyclic antide-

pressant fails, only then will her insurance cover duloxetine.