This drug is typically used in surgery or for short procedures. It can be used for patients in trauma care to help with intubation, or in those undergoing electroconvulsive therapy.
This drug is considered a neuromuscular blocking drug. It binds to the nicotinic acetylcholine receptor and keeps the receiving nerve stuck in a depolarized state.
Succincylcholine exerts its action by binding to the motor nicotinic receptor, which typically only accepts endogenous acetylcholine.
This drug mimics acetylcholine at the nicotinic receptor, opening sodium channels and causing membrane depolarization.
Succinylcholine keeps cells in sustained depolarization and prevents muscle contraction. The endogenous ligand for this receptor, acetylcholine, is removed from the receptor in second. Succinylcholine, on the other hand, is bound for much longer time. This can be observed immediately after IV administration of this drug, as patients fasciculate (contract), and are unable to contract again, even after electrical stimulation.
Phase I of this drug is characterized by maintaining the muscle cell's membrane potential above the action potential threshold. The cells are kept in a depolarized state (as succinylcholine is bound to the receptor), as succinylcholine is not broken down quickly. This period of paralysis cannot be overcome, as there is nowhere for acetylcholine to bind.
Phase II blocking of this drug is characterized by the cells being repolarized but blocked. The myocytes become sensitized to their receptor activity and eventually repolarize. ACh receptors are now available but are less sensitive to acetylcholine; they are desensitized. This paralysis is reversible, but needs a larger acetylcholine stimulus to cause contraction.
Neostigmine is an acetylcholinesterase inhibitor and prevents the breakdown of acetylcholine in the plasma. This leads to an increase in acetylcholine concentration. It is often used to overcome the desensitization experience by paralyzed patients in Phase II block of succinylcholine.
Picmonic's rapid review multiple-choice quiz allows you to assess your knowledge.
*Average video play time: 2-3 minutes
Unforgettable characters with concise but impactful videos (2-4 min each)