Classification of Skeletal Muscle Relaxants

Skeletal muscle relaxants are a group of drugs that can reduce muscle stiffness and induce temporary paralysis to relieve pain. There are two types.

Spasmolytic drugs relieve involuntary and painful muscle contractions arising from hyper-excited motor neurons found in the brain or spinal diseases or injuries.

Baclofen, a common spasmolytic, acts on spinal nerves and activates the receptors of the inhibitory neurotransmitter GABA. This prevents the excitatory neurotransmitters from firing off the motor neurons.

On the contrary, neuromuscular blockers inhibit transmission at the neuromuscular junction to induce muscle paralysis during surgical anesthesia. They can be non-depolarizing or depolarizing.

Non-depolarizing agents, such as rocuronium, prevent the action of the neurotransmitter acetylcholine by blocking the binding site on its receptor. As a result, the muscles relax.

 Depolarizing agents like succinylcholine mimic acetylcholine's action by binding to its receptors and opening sodium channels in muscle cells. The influx of sodium ions extends membrane depolarization, producing repeated muscle contractions and temporary muscle paralysis.