Cyclobenzaprine, Orphenadrine and Tizanidine

Cyclobenzaprine

It mainly acts at the level of brainstem. It has anticholinergic effect and is a good muscle relaxant. It is given orally and is metabolized by the liver.

It is usually given in combination with Methacarbamol (same group).

It is used in adjuvant therapy and in physiotherapy with other drugs.

Orphenadrine

Orphenadrine has anticholinergic activity. It has muscle relaxant effects and can be used in strychnine over dosage. However, it produces sedation, drowsiness and confusion.

Tizanidine

Tizanidine is a newer drug. It is a congener of Clonidine, which is antihypertensive drug. It acts as agonist at alpha 2 receptors and enhances pre and post synaptic inhibition.

It can be given orally but bioavailability is less because of extensive first pass metabolism. It is beneficial in patients on bed rest. Main adverse effects are similar to those of orphendadrine.