[Verse 1]
Absorption, distribution, metabolism, elimination —
Four pillars holding up your dosing calculation
Volume of distribution tells you where the drug resides
Hydrophilic stays in plasma, lipophilic deep inside tissues
Half-life times point-six-nine divided by clearance rate
Miss that number, underdose, or you accumulate
Steady state hits after five half-lives in the vein
Front-load with a loading dose or wait — that's the clinical game
Opioids bind mu receptors, potency ain't the same as dose
Morphine six-glucuronide builds up when renal function's low
Fentanyl's a lipid lover, patches lag behind the blood
Context-sensitive half-time climbing when you stop a prolonged drip — understand
[Chorus]
ADME — Absorption, Distribution, Metabolism, Excretion
PK meets PD — concentration drives the action
EC-fifty is the target where effect hits halfway
CYP enzymes flipping switches — watch what drugs you stack today
ADME — know the curve, anticipate the reaction
Titrate tight, bioavailability in the equation
[Verse 2]
Now pharmacodynamics — effect versus concentration
Sigmoid Emax model, ceiling hits at saturation
NSAIDs block COX-2, prostaglandins cut the signal
Add a mu-agonist on top — synergy, not simple
Ketamine blocks NMDA, sub-anesthetic infusion
Prevents central sensitization — opioid-sparing conclusion
Gabapentinoids cap the alpha-two-delta calcium current
Sedation stacks with opioids — respiratory risk concurrent
Know your therapeutic index, narrow means watch closely
Methadone's QT prolongation — cardiac risk, dose slowly
Buprenorphine ceiling on respiratory suppression
But partial agonist at mu means ceiling on analgesia too — pay attention
[Chorus]
ADME — Absorption, Distribution, Metabolism, Excretion
PK meets PD — concentration drives the action
EC-fifty is the target where effect hits halfway
CYP enzymes flipping switches — watch what drugs you stack today
ADME — know the curve, anticipate the reaction
Titrate tight, bioavailability in the equation
[Bridge]
CYP3A4 metabolizes codeine? — Nah, that's wrong, flip it
CYP2D6 converts codeine to morphine — ultrarapid metabolizer rippin'
Ten-percent of Caucasians carry duplicated alleles
Ultra-metabolizers flooding plasma — toxicity reveals
Poor metabolizers get zero conversion, zero relief
Tramadol same pathway — genotype beneath the belief
Serotonin syndrome lurking when you stack tramadol with SNRIs
Linezolid, methylene blue — MAO inhibition flies
Drug-drug interactions multiply when polypharmacy expands
Check protein binding — warfarin displaced by NSAIDs, now it lands
Higher free fraction means higher effect, recalculate the plan
Hepatic extraction ratio — first-pass strips the bioavailability, man