Opiates

General side effects of opiates
	
	Miosis (pupil restriction)
	Respiratory depression, but no effect on hypoxic drive ("Breathe!")
	Varying degrees of addiction & euphoria proportional to rate of effect on brain
	Intestinal receptor binding -> anti-diarrheal

Diphenoxylate (Lomitil TM)
	
	Rx diarrhea

Loperamide (Imodium TM)
	
	MOA: highly hydrophobic GI opiate receptor agonist
	OTC Rx diarrhea
	PK: very poor gut absorption -> no CNS effects & not addictive

Meperidine (Demerol TM)
	
	MOA: Mu opiate receptor agonist w/ high brain penetration
	Rx gall bladder or kidney stone pain due to lower doses and less inc of sphincter smooth mm tone

Dextromethorphan
	
	MOA: "inactive" opiate receptor agonist isomer
	Nonaddictive cough Rx (antitussive)

Morphine
	
	MOA: classic opiate agonist
	Rx severe pain, eg by patient controlled analgesia for continuous receptor occupancy

Codeine
	
	MOA: morphine prodrug converted by P450
	PK: Liver conversion slows absorption -> slower acces to brain -> less euphoria -> less addictive than morphine

Heroin
	
	MOA: morphine prodrug with spontaneous conversion
	High access to brain -> euphoria -> highly addictive
	PK: IV, short-acting (2-3 hours)

Methadone
	
	MOA: slow brain entry & long acting opiate receptor agonist
	Rx heroin addiction ("methadone maintenance")

Naloxone (Narcan TM)
	
	MOA: IV opiate receptor blocker
	Rx opiate overdose

Naltrexone (Trexan TM)
	
	MOA: oral opiate receptor blocker
	Theoretically Rx opiate addiction but not effective due to need to take regularly
	Rx alcoholism

Pentazocine (Talwin TM)
	
	MOA: mixed opiate receptor agonist-antagonist
	Rx pain, less addictive than other opiate agonists

Tramadol (Ultram TM)
	
	MOA: weak Mu opiate receptor agonist
	Rx moderate pain, but less respiratory depression and less addicting