Cyclobenzaprine hydrochloride vs cyclobenzaprine?

Short answer: They’re essentially the same drug. Cyclobenzaprine hydrochloride is the salt form of cyclobenzaprine. The active drug is cyclobenzaprine; the HCl part is just a counterion that makes the molecule more soluble and easier to formulate as a tablet or capsule.

Key points:
- What you’re taking on the label is usually “cyclobenzaprine hydrochloride” (the salt). The amount listed (e.g., 5 mg, 10 mg) refers to the amount of the salt.
- The actual active moiety is cyclobenzaprine. The amount of base is a little less than the salt; you can convert if you need to compare to a base-only dose. A rough way to think of it: base mg ≈ salt mg × (MW of base) / (MW of base + 36.46), where 36.46 is the molecular weight of HCl. In practice, 5 mg of cyclobenzaprine HCl corresponds to roughly 4–4.5 mg of base. Exact numbers depend on the precise molecular weights.
- Dosing and effects: Dosing is prescribed as mg of the salt (cyclobenzaprine HCl). The pharmacologic effect, safety profile, and approved uses are for the same active drug. There isn’t a separate “cyclobenzaprine base” product commonly used clinically.
- Why the salt: The hydrochloride salt improves solubility and stability, which helps with absorption and formulation.

If you want, I can help you calculate a specific conversion if you know the exact base MW (or the exact label you’re looking at). Also, I can summarize typical dosing, interactions, and side effects if that would help.