[Verse 1]
Prescribe codeine to the wrong patient, watch it go south
Pro-drug sitting dormant 'til CYP2D6 steps out
Poor metabolizer — enzyme barely shows its face
Codeine stacks up toxic, opioid stays in place
No morphine conversion, patient gets no pain relief
Or ultrarapid metabolizer — now that's the real grief
Six copies of the gene, metabolism so extreme
Infant nursing case, maternal codeine, fatal scene
CPIC guidelines posted on the wall
Ultrarapid plus codeine? Don't prescribe at all
[Chorus]
Two-D-six is the gatekeeper, read the phenotype
Poor, intermediate, normal, ultrarapid — get it right
Codeine, tramadol, hydrocodone running through the gate
Wrong metabolizer status means you're sealing someone's fate
Check the genome before you write, don't prescribe blind
Pharmacogenomics — the prescription's in the find
[Verse 2]
Tramadol need that same enzyme to make O-desmethyl
Ultrarapid converts excess, CNS goes to the devil
Seizure threshold dropping, serotonin syndrome creeping in
Intermediate metabolizer — therapeutic window thin
Hydrocodone likewise — CYP2D6 activation
Insufficient analgesia hits the poor metabolizer nation
CPIC says alternatives when the phenotype won't cooperate
Non-codeine opioids for the poor — that's how you navigate
Genotyping ain't guesswork, it's precision on the page
Molecular evidence directing every dosage stage
[Chorus]
Two-D-six is the gatekeeper, read the phenotype
Poor, intermediate, normal, ultrarapid — get it right
Codeine, tramadol, hydrocodone running through the gate
Wrong metabolizer status means you're sealing someone's fate
Check the genome before you write, don't prescribe blind
Pharmacogenomics — the prescription's in the find
[Verse 3]
Now OPRM1 A118G variant, mu receptor gene
Higher opioid requirements, blunted morphine scene
COMT val158met affects catechol degradation rate
Pain catastrophizing, emotional processing, modulate
ABCB1 encodes P-glycoprotein at the blood-brain fence
Variant changes CNS opioid penetrance
Clinical utility still debated, evidence limited right now
But population variability? That's the real know-how
African descent, Asian, European — allele frequencies shift
Ethnic background shapes the pharmacokineticrift
[Bridge]
HLA-B asterisk fifteen-zero-two
Southeast Asian ancestry, carbamazepine — what it do?
Stevens-Johnson syndrome, toxic epidermal wrecking
FDA says test before prescribing — no second-guessing
Han Chinese, Thai, Malaysian population screen
Hypersensitivity written in the HLA machine
Genetic testing indications: high-risk ethnicity
Polypharmacy complexity, pediatric safety decree
[Chorus]
Two-D-six is the gatekeeper, read the phenotype
Poor, intermediate, normal, ultrarapid — get it right
Codeine, tramadol, hydrocodone running through the gate
Wrong metabolizer status means you're sealing someone's fate
Check the genome before you write, don't prescribe blind
Pharmacogenomics — the prescription's in the find