Two medicines, side by side
Chlorzoxazone vs orphenadrine
Chlorzoxazone and orphenadrine are both labeled for muscle spasms and spasticity. Drugs@FDA records approvals of chlorzoxazone since 1958 and of orphenadrine since 1957. Pharmacies paid $0.210 per chlorzoxazone 500 mg tablet and $0.454 per orphenadrine ER 100 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like.
Check it at the source: the chlorzoxazone FDA label on DailyMed (effective September 5, 2023); the orphenadrine FDA label on DailyMed (effective September 10, 2025).
Highlights of the chlorzoxazone record
Chlorzoxazone (Parafon Forte Dsc) · label of September 5, 2023
Used for
From the label: indicationsChlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.
On the market
- Earliest approval on file
- August 15, 1958
- Generic labelers
- 19 labelers
- Pharmacy cost
- $0.210 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 2
Highlights of the orphenadrine record
Orphenadrine (Disipal) · label of September 10, 2025
Used for
From the label: indicationsOrphenadrine citrate extended-release tablets are indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute painful musculoskeletal conditions.
On the market
- Earliest approval on file
- May 10, 1957
- Generic labelers
- 17 labelers
- Pharmacy cost
- $0.454 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 3
Source: FDA drug labels via openFDA (Chlorzoxazone label of September 5, 2023, Orphenadrine label of September 10, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do chlorzoxazone and orphenadrine differ on the record?
Both are in FDA's class muscle relaxants.
Generics: chlorzoxazone since 1981; orphenadrine since 1981 (Drugs@FDA).
| Chlorzoxazone | Orphenadrine | |
|---|---|---|
| Labeled for | Muscle spasms and spasticity | Muscle spasms and spasticity |
| Pharmacologic class | Muscle Relaxant | Muscle Relaxant |
| How it works (label) | n/a | n/a |
| Half-life (label) | n/a | n/a |
| Earliest approval on file (Drugs@FDA) | August 15, 1958 | May 10, 1957 |
| First generic approved | October 6, 1981 | July 16, 1981 |
| Generic labelers (NDC) | 19 labelers | 17 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.210 per tablet (Chlorzoxazone 500 mg tablet) | $0.454 per tablet (Orphenadrine ER 100 mg tablet) |
| 12-month price change | -5% | +6% |
| Boxed warning | No | No |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 2 | 3 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 1,296 | 621 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What next?
- Alternatives to chlorzoxazone
- every medicine labeled for the same conditions