Rifapentine is a semisynthetic rifamycin-class antimycobacterial active pharmaceutical ingredient used in pharmaceutical formulations for the treatment of tuberculosis and latent tuberculosis infection. It inhibits bacterial DNA-dependent RNA polymerase and interferes with bacterial RNA synthesis.
Rifapentine is identified by CAS No. 61379-65-5, molecular formula C₄₇H₆₄N₄O₁₂, and molecular weight approximately 877.04 g/mol. It is also identified by FDA UNII XJM390A33U, ChEBI CHEBI:45304, and DrugBank DB01201.
WHO lists Rifapentine as a prequalified active pharmaceutical ingredient, with Lupin Ltd. listed as an assessed API manufacturer.
Rifapentine belongs to the rifamycin/ansamycin antibiotic class and is structurally related to rifampicin while having a cyclopentyl-substituted piperazine side chain.
The API is generally described as a red to brown or reddish crystalline powder. It has very low aqueous solubility, making solid-state characteristics and particle-size control important considerations during pharmaceutical manufacturing. WHO's assessment of Rifapentine-containing products specifically considers the API's physicochemical and quality characteristics.
Rifapentine is used in combination with other anti-tuberculosis medicines rather than as monotherapy for active TB.
| Parameter | Details |
|---|---|
| Product Name | Rifapentine |
| Synonyms | Priftin, Rifapentin, Cyclopentylrifampicin, Rifamycin AF/ACPP, MDL 473 |
| CAS Number | 61379-65-5 |
| Molecular Formula | C₄₇H₆₄N₄O₁₂ |
| Molecular Weight | 877.04 g/mol |
| FDA UNII | XJM390A33U |
| ChEBI | CHEBI:45304 |
| DrugBank | DB01201 |
| ATC Code | J04AB05 |
| API Class | Rifamycin / Ansamycin antibiotic |
| Therapeutic Class | Antimycobacterial |
| Appearance | Red to brown / reddish crystalline powder |
| Water Solubility | Practically insoluble / very slightly soluble |
| Melting Point | 174°C reference value |
| Maximum Absorption | 475 nm reference value |
| Storage Reference | Protect from moisture and heat; validated API stability conditions apply |
PubChem confirms the identity, CAS number, molecular formula, molecular weight and major identifiers. TCI reports a reference melting point of 174°C and maximum absorption wavelength of 475 nm.
Rifapentine API is primarily used in pharmaceutical products intended for tuberculosis management.
Rifapentine is used in combination with other antimycobacterial medicines for the treatment of active tuberculosis caused by susceptible Mycobacterium tuberculosis.
Rifapentine is also used in combination treatment regimens for latent tuberculosis infection to reduce the risk of progression to active TB.
Rifapentine API is used for the manufacture of:
WHO currently lists prequalified Rifapentine 150 mg dispersible tablets and Isoniazid/Rifapentine products.
Rifapentine requires comprehensive pharmaceutical quality control covering identification, assay, related substances, water content, residual solvents, physical properties and solid-state characteristics
The numerical values marked with an asterisk are published commercial/CP specifications and should not be presented as a universal USP specification. WHO confirms that accepted API specifications exist but notes that the accepted detailed specification and analytical methods may be provided through the API manufacturer rather than fully disclosed publicly.
TCI currently reports minimum 98.0 area% HPLC purity, minimum 97.0% nonaqueous titration, and a reference melting point of 174°C.
Rifapentine quality control can include:
A recent 2026 stability-indicating LC method for Rifapentine reported HPLC assay results and validated impurity detection at low levels, supporting the use of chromatographic impurity profiling for routine quality control.
Rifapentine API manufacturing requires controlled synthesis, purification and pharmaceutical quality testing because of the molecule's complex rifamycin structure and physicochemical characteristics.
Important manufacturing controls include:
WHO's API prequalification list currently identifies Lupin Ltd. as a prequalified Rifapentine API applicant, with the API prequalification dated 10 June 2024 and confirmation dated 29 April 2026.
WHO also identifies Indian Rifapentine API manufacturing sites associated with prequalified products, including sites of Lupin and Macleods.
Rifapentine API should be stored in suitable pharmaceutical-grade, well-closed packaging that protects the material from moisture, light and excessive heat.
Commercial reference material from TCI is stored frozen at −20°C under inert gas and is identified as moisture- and heat-sensitive. This is a commercial reference-material condition and should not automatically be used as the universal pharmaceutical API storage condition.
For finished Rifapentine pharmaceutical products, WHO-prequalified products are stored not above 30°C and protected from moisture.
Typical Rifapentine API documentation may include:
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Residue on Ignition | NMT 0.20% |
| Heavy Metals | NMT 20 ppm |
| Individual Impurity | NMT 1.0% |
| Total Impurities | NMT 3.0% |
| Water Content | NMT 5.0% |