Pharma-grade castor oil is castor oil that is processed, tested and documented to meet a pharmacopoeia monograph, usually USP, EP or both. Whether you need USP or EP depends on where the finished medicine is sold and what your customer's regulatory file names.
It is not a different oil. It comes from the same seed as industrial grades, but the refining, testing and paperwork are stricter, and the plant should work to good manufacturing practice for excipients.
What a monograph covers
USP is the United States Pharmacopeia. EP, also written Ph. Eur., is the European Pharmacopoeia. The British, Indian and Japanese pharmacopoeias also have castor oil monographs. Each monograph sets identity tests, quality limits and the test methods to use. The European Pharmacopoeia separates virgin and refined castor oil, so check which one your formulation names.
Typical parameters in a castor oil monograph include the following. Exact limits differ between pharmacopoeias and editions, so always work from the current text rather than a supplier's summary.
- Identification, often including fatty acid composition, where ricinoleic acid dominates.
- Acid value, hydroxyl value, iodine value and saponification value.
- Peroxide value and unsaponifiable matter.
- Water content, relative density and refractive index or optical rotation.
- Impurities such as residual solvents or elemental impurities, where the monograph or your risk assessment calls for them.
Do you need USP or EP?
There is no single answer. It depends on the market and the product.
- Medicines for the US: the oil is normally expected to meet the USP monograph where one exists.
- Medicines for the EU: the European Pharmacopoeia is legally binding in its member states, so EP compliance is the norm. UK practice follows the British Pharmacopoeia, which includes the European monographs.
- Products for several markets: many buyers ask for dual USP and EP compliance on one batch.
- Cosmetics and industrial uses: a pharmacopoeia grade is not legally required, but some buyers use it as a quality benchmark.
A label is not a certificate
USP and EP do not certify factories or approve suppliers. When a supplier says its oil is USP grade, that is a claim that each batch passes the monograph tests. Ask for the full certificate of analysis against the current edition, with the method for each test, and have a retained sample checked at an independent lab. Our guide to reading a lab certificate explains what to look for.
For a refresher on the core quality numbers, see what acid value, iodine value and colour castor oil should have.
What else the plant should show
- A quality system that follows excipient GMP guidance, and in some cases third-party excipient GMP certification.
- Batch traceability from seed lots through pressing, refining and filling.
- Change control, so you are told before the process, site or seed source changes.
- Clean, dedicated or validated filling lines and food or pharma-suitable drums.
- Supporting documents your customer may ask for, such as allergen and TSE statements, stability or retest data, and in some cases a drug master file filed with the US FDA.
How we help
We look for castor oil plants that already supply pharma customers, audit their refining, filling and quality records, and have batch samples tested against the monograph at an NABL-accredited lab. You see the real plant name and the original reports. To start, ask for a free sourcing review.