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32 Cards in this Set

  • Front
  • Back
Ach receptor types
Muscarinic: G-coupled proteins
Nicotinic: ligand-gated, multi-unit proteins
The nicotinic receptor
ligand-gated channel composed of five subunits. It is primarily the responsible for the peripheral effects of acetylcholine at the autonomic ganglia and the neuromuscular junction.
Acetlycholine receptors are multi-subunit membrane spanning proteins consisting of five distinct subunits; (a,b,d,g).
Acetylcholine binds to the a subunits, of which there are two on each of the acetylcholine receptor ion channels.
Once bound, acetylcholine causes ligand-gated ion channels in the post synaptic membrane to open.
These channels are relatively non-selective so the passage of different ions, such as Na+, K+ and Li+ occurs.
Nicotinic locations
sympathetic-adrenal medulla
sympathetic first synapse
parasym first synapse
striated muscle
Agonists and indirect agonists
ACh-like drugs (methacholine, carbacholine, nicotine)
Bind and activate nicontinic ACh receptors
Not destroyed by AChE so the effects are prolonged

Anti-AChE (neostigmine, physostigmine, disopropyl fluorophosphate or “nerve gas”, and insecticides)
Block the degradation of ACh, thereby prolonging it’s effects
block nicotinic aCh channels by competing for aCh binding site

reduces amplitude of end plate potential thereforre, no AP
inhibitors-botulism toxin
decreases the release of Ach from nerver terminal

isufficient stimulus to initiaate the AP

Two of the oldest known molecules
Ganglionic Blockers
Ganglionic Blockers

Neuromuscular blockers
Rocuronium (Roc)
Succinylcholine (Sux)
Vecuronium (Vec)

Rocuronium (Roc)
Succinylcholine (Sux)
Vecuronium (Vec)
GABA Receptors
They are the main inhibitory receptors, mostly found in the CNS.
They are involved with many neuroactive drugs.
There are 3 subtypes of GABA receptors
GABA A and GABA C- Ligand or voltage-gated Chloride ion channels, an “ionotropic receptor”,
which are opened in response to the GABA neurotransmitter or other drugs like volatile anesthetics, alcohol, steroids, Benzodiazepines, Barbiturates and Anticonvulsants. GABA A’s are the most common type.
GABA B- is a G Coupled Protein
a “metabotropic receptor”, that regulates biochemical pathways and/or ion channels. Baclofen (used for muscle spasticity) is an agonist and Saclofen is an antagonist.
GABA A Receptors
When GABA A receptors are activated, chloride ions rush inside the cell. This activity hyperpolarizes the cell, so the cell cannot depolarize. This action is inhibitory. The various protein subunits of the receptor are each specific for a certain type of substance as shown.
GABA B Receptors
GABA B receptors belong the G Protein Couple Family (GPCF) of receptors. When the receptor is activated, it stimulates a G Protein, attached to it inside the cell, to release a subunit which activates (think phosphorylation, cAMP, cGMP, etc.) either a biochemical pathway (an enzyme system) or an ion channel.
Barb history
Drugs that act on CNS as depressants
Derived from Barbituric Acid
Acts on GABA-A receptor
Wide spectrum of effects-mild sedation to anesthesia
more barb history
Discovered in 1864 by Adolf von Baeyer
1903- 1st medicinal barbiturate
1912- Phenobarbital introduced as sedative hypnotic
1950’s- Reports about dependance related to barbiturates
1970- Barbiturates become controlled substances
Uses of Barbiturates
Induction of anesthesia

Treatment of increased ICP

Treatment of seizures

Treatment of Hyperbilirubinemia

Treatment of kernicterus
Barb-Induction of Anesthesia
Gold standard from 1934-1989
Given IV, has CNS effects within 30 secs
Virtually no side effects on skeletal, cardiac, and smooth muscle
Propofol is used in place of most barbiturates
Increased ICP treatment
Decreases cerebral blood volume by causing vasoconstriction and decreased blood flow
Seizures treatment
Enhance GABA activity

General depressant of nerve and muscle tissue
Hyperbilirubinemia and Kernicterus treatment
Increases hepatic glucuronyl transferase activity
Non-Therapeutical barb Uses
Physician assisted suicide


Lethal injection
Barb SAR
Inactivated structures don’t have carbon chains at the 5th position. The sulfur on the thiobarbiturate causes an increase in lipophilicity thus a more rapid onset and shorter duration with quicker recovery.
Barb SAR
Hypnotic Activity: Side chains at position 5 (especially if one of them is branched).
Potency and duration of action: Length of side chain at position 5 (so secobarbital and thiamylal are slightly more potent than pentobarbital and thiamylal are slightly more potent than pentobarbital and thiopental, respectively.
More rapid onset and shorter duration of action: Sulfur instead of oxygen atom at position 2 (so thiamylal and thiopental have more rapid onset and shorter duration of action than secobarbital and pentobarbital, respectively.)
Increased incidence of excitatory side effects: Methylation at position 1 (methohexital).
Stereoisomerism: Though their levo-isomers are nearly twice as potent as their dextro-isomers, barbiturates are marketed as racemic mixtures. Methohexital has two asymmetric carbon atoms, so exists as 4 stereoisomers (alpha, beta, dextro, levo, methohexital).
Primary Barbiturates Used in Anesthesia
Sodium Thiopental (Sodium Pentathal)
Introduced in 1936
Methohexital (Brevital)
Introduced 1952
Barb SAR
Side Chains at Number 5 Allow for Increased Hypnotic Activity and Increased Potency (For Both)
Sulfur on Number 2 of Thiopental Allows for More Rapid Onset and Shorter Duration of Action (“Ultra Short-Acting”)
Methylation on number 1 of methohexital causes increased incidence of excitatory effects.
Convulsions were common when methohexital was introduced but isolation and elimination of the beta isomer has decreased the incidence of seizure activity to only increasing the chances of seizures in those individuals who already have a pre-existing seizure disorder. Methohexital is marketed as racemic alpha –d,l-methohexital.
CNS barbiturate S/A's?
Unusual excitement
Unusual tiredness or weakness
Decrease or loss of reflexes
Poor judgment, slurred speech
Insomnia, nightmares
Unusual movements of the eyes
Dizzy or lightheadedness
Anxiety or nervousness
Visual changes
Cardiovascular barbiturate S/A's?
Chest pain
Unusual bleeding or bruising
Repiratory barbiturate S/A's?
Wheezing or tightness in chest
SOB, slow or troubled breathing
GI/GU barbiturate S/A's?
Loss of appetite
Nausea or vomiting
Difficulty urinating
Dry mouth
Musculoskeletal barbiturate S/A's?
Muscle or joint pain
Bone pain, tenderness, or aching
Muscle weakness
Staggering, clumsy, or unsteadiness
other barbiturate S/A's
Bleeding sores on lips
Red, thickened or scaly skin
Yellow eyes or skin
Rash or hives
Sores, ulcers, or white spots in mouth (painful)
Sore throat
Swelling of eyelids, face or lips
Weight loss (unusual)
Low body temp
Decreased libido
An overdose can cause Resp/cardiac depression & DEATH