Orphenadrine
"Took 50 mg - cut a 100 mg ER pill in half, for muscle relief a few weeks after a minor car accident. Am 125 pounds. 
Over 20 hours later, still affected by droopiness, tiredness, and mild headache. Took a long walk and could barely get through it, ended up falling asleep in the afternoon.

On the plus side, muscle and joint pain was negligible today. However, also couldn't think or do much either. Would not take again."