Barbiturates

Question 1

Name Barbiturates

Answer 1

Thiopental
(“The Ol’ quick shave”)
Primidone
(“Perm is done!” primadona)
Phenobarbital

Question 2

Barbiturates MOA

Answer 2

-GABA-A receptor is a chloride channel,chloride influx hyperpolarizes nerve cells
(“chlo-rider” sign on Cab-A)

-potentiates (enhance) transmission of GABA in CNS
(“Red CNS light on Cab-A”)

-GABA is the major inhibitory neurotransmitter in the CNS (the sign on Cab-A says “take it easy” )

-binds to a separate allosteric site on GABA-A Receptor
(“barber opening dooe on other side of Cab-A driver Pamcakes”)

-Barbiturates increase the duration of opening of the GABA-A receptor chloride channel
(sign at entrance of shop saying :”long hair? now open longer”)

-Barbiturates have long duration of action and therefore “hangover” effects are more common
(“long tapering flag outside barber shop”)

Question 3

Barbiturates Pharmacokinetics

(mainly Thiopental here?)

Answer 3

-Barbiturates have long duration of action and therefore “hangover” effects are more common
(“long tapering flag outside barber shop”)

• Thiopental has rapid onset and short duration of action because it’s highly lipid soluble
• plasma levels of Thiopental decrease rapidly due to redistribution to skeletal muscle and adipose

(“barber cuts hair and redistributes it to arms and belly of customer”)

Redistribution graphof Thiopental (on customer’s chest)

Decay line - rapid decay of plasma Thiopental

Brief peak - rapid accumulation of thiopental in brain and rapid redistribution

Growth line-rapid accumulation of Thiopental in skeletal muscle and adipose(recovery from anesthesia)

Question 4

what are Barbiturates used for ?

Answer 4

IV-adminstration of Barbiturates (“Ivy on pole”)

-IV adminstration of Thiopental can be used for induction of anestehsia since its highly lipid soluble and enters the CNS quickly.
(intubated customer getting “The Ol’ quick shave”)

-IV adminstration of Phenobarbital can be used to treat Seizures
(“coworker outside unplugging jackhammer”)

-Primidone (“perm is done!”) can be used to treat seizures and essential tremors - 1st line with propanolol
(“prima dona’s barber has tremulous hand”)

Question 5

Barbiturates side effects

Answer 5

-chronic use of barbiturates leads to tolerance
(“all are welcome” sign in entrance of barbershop)

-chronic barbiturates use leads to physical dependence
(“addicted to curls” sign)

-can cause hypotension
(“fainted old fart sitting on hair dryer chair”)

-can cause profound cardiac and respiratory depression
(“old fart has collapsed heart and lungs t-shirt”)

-can cause severe CNS depression (coma) ,should be avoided in elderly
(“brain shaped hair dryer”)

-barbiturates are potent inducers of the CYP450 which may increase metabolism of drugs such as warfarin
(activated chrome bumper plate saying “CYP450”)