Japanese Pharmacopoeia vs USP and Ph. Eur.: a supplier guide

The JP is law, and the Japanese text is the edition that counts

The JP is not a reference book in Japan. PMD Act Article 41 has the Minister of Health, Labour and Welfare establish it, after hearing the Pharmaceutical Affairs Council, to set the properties and quality of drugs.

Its five parts are the General Notices, the General Rules for Crude Drugs, the General Rules for Preparations, the General Tests and the Official Monographs. MHLW describes the monographs as centered on drugs widely used in Japan.

The law also fixes its rhythm. The Council must review the whole JP at least every ten years. The current edition is the 19th, MHLW Notification No. 193 of 2026, published and in force on April 10, 2026. It holds 2,072 monographs: 27 new, 3 deleted and 147 revised. MHLW has already issued errata, on June 29 and September 30, 2026, and the Council reported the basic policy for the 20th edition on August 27, 2026.

There is a transition. MHLW's implementing notice of April 10, 2026 lets products affected by the revision follow the previous standards until September 30, 2027. From October 1, 2027, a product that does not meet JP19 may not be marketed.

The English text lags. MHLW's JP page lists English versions of the 18th edition and both of its supplements, the second of which took effect in June 2024. It lists none for the 19th. PMDA and MHLW publish their English texts for convenience; where they differ, the Japanese text prevails.

You can still shape the next text. PMDA posts draft monographs on its Japanese site at the start of March, June, September and December, with one or three months for comments. It posts English drafts as well and, as a trial, accepts comments in English from outside Japan, though it does not answer each one. The drafts for JP19's first supplement went up in September 2026.

Check each JP statement you issue against the Japanese text of JP19 and its two errata, because the English JP18 on your file is no longer the current edition.

Article 56 makes the JP, or the customer's approval, bind each lot

The force of the JP comes from Article 56 of the PMD Act. It lists drugs that may not be sold, given, or made or imported for sale.

The first item covers a drug listed in the JP whose properties or quality fail the JP's standards. Two exceptions follow. One is a product approved with its properties and quality judged appropriate. The other is a material used to make such an approved product. A separate item bans an approved drug whose quality differs from what its approval states.

Read together, the two items move the question to your customer's approval. If the approval names your material as JP grade, each lot has to meet the JP monograph. If the approval sets a different specification that PMDA accepted, that specification binds instead.

This is why the request for a "JP conforming" certificate matters. A certificate tested only to USP-NF may leave your customer unable to show that a lot meets the standard its approval names.

Ask each Japanese customer which standard its approval names for your material, JP, JPE or its own specification, because that wording decides what every lot must meet.

Harmonized does not mean identical

Harmonization runs through the Pharmacopoeial Discussion Group (PDG). Its members are the European, Indian, Japanese and United States pharmacopoeias. The Indian Pharmacopoeia Commission joined in October 2023, and the group's Japanese name changed the same month.

PMDA publishes where each harmonized excipient monograph stands in the JP. Its table, as of September 11, 2026, lists 63 excipients. Forty-eight carry a JP title, and 15 are still marked "harmonization work in progress". The fifteen include Purified Water, Water for Injection, Glycerin, Propylene Glycol, Polyethylene Glycol, Polysorbate 20 and Carmellose Sodium.

A harmonized monograph still has local parts. Each PDG sign-off cover sheet lists the harmonized attributes, the non-harmonized attributes and the local requirements, and PMDA links every one. In the JP text, non-harmonized parts sit between black diamonds (◆) and the JP's own additions between white diamonds (◇). PMDA said in September 2026 that texts harmonized from October 2025 will carry black diamonds only. It plans to apply the change across the JP in the 20th edition.

Names differ too. The JP calls Lactose Monohydrate "Lactose Hydrate", Cellulose Acetate Phthalate "Cellacefate", Mannitol "D-Mannitol" and Methyl Paraben "Methyl Parahydroxybenzoate". Search Japanese documents by the JP name.

Implementation also lags signature. Revision 2 of the hypromellose monograph was signed on September 13, 2017 and took effect in the JP on June 28, 2019. A new version of the dibasic calcium phosphate cover sheet was signed on September 3, 2026, and PMDA's table shows no JP date for it yet.

For every excipient you sell into Japan, pull the PDG cover sheet from PMDA's table and confirm that your certificate covers each non-harmonized attribute and local requirement as the JP states it.

Excipients outside the JP have their own Japanese book

Many excipients are not in the JP at all. For them Japan keeps a separate standard, the Japanese Pharmaceutical Excipients, abbreviated JPE.

The current text is JPE2018, issued by MHLW notice on March 29, 2018. It holds 489 items, with general rules, general tests and monographs. MHLW revised it on December 10, 2019, March 7, 2022 and March 28, 2024, and issued errata as late as March 28, 2025. Each revision came with a notice on how marketing applications should handle it. MHLW also posts a consolidated version, marked as reference only.

Two practical points follow. A specification that cites JPE2018 may mean the 2018 text or a later revision, so the revision matters. And the consolidated version is not the legal text, so the revision notices decide any difference.

If your excipient is in JPE rather than the JP, ask which revision your customer's approval cites and test to that text, using the revision notices rather than the consolidated reference version.

For excipients, precedent of use is the sharper question

Monographs settle quality. Japan asks a second question about safety, and it often decides whether a customer can use your excipient at all.

The rule dates from an MHLW notice of March 31, 2005 on marketing applications. An application must include quality and safety data on an excipient in three cases. One is an excipient never used in an approved drug. The others are a known excipient used by a different route or at an amount above the precedent.

Precedents are recorded by route and by maximum daily amount. The Japanese Pharmaceutical Excipients Directory 2021 covers 1,442 excipients, and PMDA keeps its own database. Since April 2017, applicants for new and generic drugs have had to submit the factors PMDA uses to calculate maximum daily amounts. On December 1, 2023, PMDA said it would take precedent data at any time and publish what it has checked, instead of waiting for MHLW surveys every few years. It asks for precedents missing from the Directory and amounts above the Directory's maxima.

A precedent can also be narrower than an approval. PMDA publishes excipients accepted only for a specific product. The lipid nanoparticle components of Onpattro, Spikevax and Kostaive are on that list, not treated as general precedents. PMDA's reasons include liver enzyme rises in toxicity studies and unproven safety for use without a time limit.

When your excipient falls outside precedent, the data travels with the customer's application. A supplier can register a new excipient in the Master File and keep its process data confidential.

Before you offer a grade for a new route or a higher dose in Japan, check the Directory and PMDA's published precedents, because beyond them your customer must file quality and safety data on your excipient.

Steps for an excipient or raw material supplier

Take these in order. The first three need nothing from your customers.

1. List every material you sell into Japan and mark whether it is in JP19, in JPE2018 or in neither, using the JP names.
2. For JP items, compare your specification with the Japanese JP19 monograph and the errata of June 29 and September 30, 2026, and note the September 30, 2027 transition date.
3. For harmonized excipients, download the PDG cover sheet from PMDA's table and confirm your certificate covers every non-harmonized attribute and local requirement.
4. Ask each customer which standard and revision its approval names for your material, and record the answer by product.
5. For a new route or a higher amount, check the Excipients Directory 2021 and PMDA's published precedents, and agree with the customer who prepares the quality and safety data, or whether you file a Master File.
6. Watch PMDA's quarterly JP drafts (March, June, September and December), including the drafts for JP19's first supplement posted in September 2026, and comment in English where a draft affects your material.
7. Reissue your JP statements when the English JP19 appears, at each supplement, and when a PDG cover sheet changes.

For the Japanese terms on customer questionnaires, see the side box and the glossary.