What is the recommended dosage of Cyclopam (Cyclobenzaprine) when administered intramuscularly?

Cyclopam Intramuscular Dosing

There is no established intramuscular formulation or dosing regimen for Cyclopam (dicyclomine/cyclobenzaprine combination) or cyclobenzaprine as a single agent, as these medications are only available and approved for oral administration.

Critical Clarification on Cyclopam

The term "Cyclopam" typically refers to a combination product containing dicyclomine (an anticholinergic/antispasmodic) and paracetamol (acetaminophen), commonly used in some countries for abdominal pain and cramping. This is not the same as cyclobenzaprine, which is a muscle relaxant used for skeletal muscle spasm.

Cyclobenzaprine: Oral Administration Only

Cyclobenzaprine is exclusively available as an oral medication and has no intramuscular formulation. The approved dosing regimens are:

• Standard dose: 5 mg three times daily, which demonstrates equivalent efficacy to 10 mg three times daily with lower sedation rates 1
• Alternative dose: 10 mg three times daily for patients requiring higher doses 1
• Lower dose: 2.5 mg three times daily was not significantly more effective than placebo and is not recommended 1

Pharmacokinetic Considerations

• Oral bioavailability is 0.55 with plasma clearance of 689 ml/min 2
• Effective half-life is 18 hours with approximately fourfold accumulation at steady state 2
• Elderly patients require dose reduction as steady-state concentrations are twice as high compared to younger patients 2
• Patients with hepatic insufficiency also demonstrate up to twofold higher steady-state concentrations 2

Common Pitfalls to Avoid

• Do not attempt intramuscular administration of oral cyclobenzaprine formulations, as there is no safety or efficacy data for this route
• Sedation is the most common adverse effect, occurring in >30% of patients, likely mediated through noncompetitive antagonism of central histamine H1 receptors 3
• The 5 mg three times daily regimen provides optimal balance between efficacy and tolerability compared to higher doses 1

Alternative Muscle Relaxants with IM Formulations

If intramuscular muscle relaxation is required, consider benzodiazepines such as:

• Lorazepam IM: 0.05 mg/kg for acute muscle spasm (dose reduced in elderly) 4
• Diazepam IV: For muscle relaxation when IV access available, though requires careful respiratory monitoring 5