Question

What is the difference between the muscle relaxants dantrolene and baclofen?

Answer 1

Dantrolene is directly acting muscle relaxant.Dantrolene acts on the RyR which is Ryanodine Receptor
calcium channels in the sarcoplasmic reticulum
of skeletal muscles and prevents their depolari-
zation triggered opening. Intracellular release of
Ca2+ needed for excitation-contraction coupling
is interfered with. Fast contracting ‘twitch’
muscles are affected more than slow contracting
‘antigravity’ muscles.
Dantrolene is slowly but adequately absorbed
from the g.i.t. It penetrates brain and produces
some sedation, but has no selective effect on poly-
synaptic reflexes responsible for spasticity. It is
metabolized in liver and excreted by kidney with
a t½ of 8–12 hours.
Used orally dantrolene (25–100 mg QID)
reduces spasticity in upper motor neurone
disorders, hemiplegia, paraplegia, cerebral palsy
and multiple sclerosis. However, it also reduces
voluntary power; the resulting weakness consi-
derably neutralizes the benefit.

Baclofen is an analogue of the inhibitory
transmitter GABA acts as a selective GABAB
receptor agonist.Baclofen does not affect Cl¯ conductance and its actions are not antagonized by bicuculline.
The primary site of action of baclofen is
considered to be in the spinal cord where it
depresses both polysynaptic and monosynaptic
reflexes. As such, it does produce muscle weak-
ness, but is less sedative than diazepam. It reduces
spasticity in many neurological disorders like
multiple sclerosis, amyotropic lateral sclerosis.baclofen is absorbed orally.