In medicine regulation, an active pharmaceutical ingredient (API) is the substance in a medicine that is meant to produce the treatment effect. It is also called the drug substance. European Union (EU) law calls it the active substance. Everything else in the finished medicine, apart from the packaging, is an excipient. An excipient is an ingredient with no intended treatment effect, such as a carrier oil or a flavouring.
The international rules for making APIs are in a guide called ICH Q7. ICH is an international council where medicine regulators and the pharmaceutical industry agree on common technical guidelines. ICH Q7 is a guide to good manufacturing practice (GMP). GMP is the set of quality rules a factory follows so that every batch of medicine is made the same way and is safe.
ICH Q7 defines an API by three conditions:
- It is a substance, or a mixture of substances, intended for use in making a drug product (a finished medicine).
- It becomes the active ingredient of that drug product.
- It is meant to have a pharmacological effect (an effect on how the body works) or another direct effect. That effect can be in diagnosing, curing, easing, treating or preventing disease. It can also be a change to the body’s structure or function.
Translator’s note: Most growers in Thailand and Southeast Asia will never make a medicine. But if you sell flower to an extraction company, a hospital or a medicine maker, these terms decide which quality rules apply to your crop. The buyer’s paperwork may call your flower a “starting material”, an “active substance” or a “finished product”. Each label means different records and checks. On the farm side, the matching standard is good agricultural and collection practice (GACP). GACP is the quality standard for growing and harvesting medicinal plants. Thailand has its own GACP standard for cannabis. Ask each buyer whether they require GACP certification from your farm.
What to do first: list every buyer of your flower. Next to each name, write what the buyer will do with it: dispense it to patients, extract it, or put it into a herbal product. You will use this list in the sections below.
The official definitions in one table
The table brings together definitions from two documents. One is ICH Q7. The other is Directive 2001/83/EC, the main EU law on medicines for human use. The examples only illustrate each term.
| Term | What it means (source) | Example |
|---|---|---|
| API / active substance | A substance intended to become the active ingredient of a medicinal product (ICH Q7; Directive 2001/83/EC) | Purified cannabidiol (CBD) used to make an oral solution |
| Excipient | Any part of a medicinal product other than the active substance and the packaging material (Directive 2001/83/EC) | The carrier oil or flavouring in that solution |
| Drug product (medicinal product) | The dosage form in its final immediate packaging, intended for sale (ICH Q7) | The filled, labelled bottle |
| Intermediate | Material made during API processing that still needs further molecular change or purification before it becomes an API (ICH Q7) | A crude plant extract waiting to be purified |
| API starting material | A raw material, intermediate or API used to make an API, which becomes a significant part of the final API’s molecular structure (ICH Q7) | Mainly relevant when the API is built by chemical synthesis |
Two terms in the table need a short explanation. “Dosage form” is the form the patient takes, such as an oral solution or a capsule. “Immediate packaging” is the container that touches the medicine, such as the bottle.
The EU law adds more detail on what an active substance does. It acts on the body in one of three ways: pharmacological, immunological (through the immune system) or metabolic (through the body’s chemistry). This action restores, corrects or changes how the body functions. An active substance can also be used to make a medical diagnosis.
Both texts rest on one idea: intent. A substance is an API because of the role it is given in a medicinal product. Its chemistry alone does not decide it.
What to do: when a buyer’s specification or contract uses “API”, “intermediate” or “starting material”, match each word to this table. That tells you whether the buyer treats your material as the active part of a medicine or as an earlier stage.
Which GMP rules apply to an API
APIs have their own GMP guide:
- In the EU, it is Part II of EudraLex Volume 4. EudraLex is the EU’s collection of medicine rules, and Volume 4 contains the GMP guidelines. Part II is titled “Basic requirements for active substances used as starting materials”.
- Under PIC/S, API rules are also in Part II of the GMP guide. PIC/S (Pharmaceutical Inspection Co-operation Scheme) is a network of national medicine inspectorates that use a shared GMP guide. PIC/S took its Part II text from ICH Q7, which it adopted in 2001.
ICH Q7 covers APIs made in any of these ways, or by a combination of them:
- chemical synthesis;
- extraction;
- cell culture or fermentation;
- recovery from natural sources (taking the substance out of natural material, such as plants).
Extraction and natural sources are inside this scope. So the guide applies to anyone who isolates cannabinoids from plant material.
ICH Q7 also has a table that lists the manufacturing steps for each kind of API. Three rows involve plants:
- An API extracted from plants, and a herbal extract used as an API (two separate rows). The steps run: collecting the plants → cutting and first extraction → purification or further extraction → physical processing → packaging.
- An “API consisting of comminuted or powdered herbs”. Comminuted means cut or ground into small pieces. This row shows that plant material itself can be the API in some settings.
ICH Q7 does not apply to the steps that come before the defined API starting material enters the process.
Translator’s note: Thailand’s Food and Drug Administration (อย.) has been a PIC/S participating authority since August 2016. Ask the Thai FDA or your extractor whether PIC/S GMP Part II applies to a given cannabinoid API made in Thailand. If it does, a Thai extractor making a cannabinoid API for medicines works under the Part II rules described here. Growing the plants happens before the API starting material enters the process, so the farm is outside ICH Q7. The flower section below shows which standard covers the farm steps instead.
What to do: if you supply an extractor, ask two questions. Which GMP guide does their facility follow? At which step does their GMP start? The answers show you where your records must end and where theirs begin.
When a cannabinoid is an API
The clearest cases are single, well-defined cannabinoid substances used to make an authorised (officially approved) medicine:
- Dronabinol is a synthetic (lab-made) delta-9-THC. It is the active ingredient in Marinol and Syndros, two medicines approved in the United States.
- Nabilone is a synthetic compound with a structure similar to THC. It is the active ingredient in Cesamet.
- Cannabidiol (CBD): the US Food and Drug Administration (FDA), the US medicine regulator, describes Epidiolex as containing a purified form of the drug substance CBD.
Official quality standards support this. A pharmacopoeia is an official book of quality standards for medicines and their ingredients. Each standard in it is called a monograph, and it lists the tests and limits a material must meet. The European Pharmacopoeia adopted two monographs, “Cannabis flower” and “Cannabidiol isolated from Cannabis sativa L.”, with an implementation date of 1 July 2024.
A monograph only sets quality requirements. It does not make a batch an API. API status comes from two things: how the material is used, and the GMP under which it is made.
Translator’s note: In Thailand, extracts have their own licensing rules. The Ministerial Regulation on Cannabis or Hemp Extracts B.E. 2569 has been in force since 26 April 2026. Licences for extracts with more than 0.2% THC are given only to three groups. The first is Thai juristic persons (registered companies or other legal entities) that are not “foreign” under the Foreign Business Act B.E. 2542. The other two are state agencies and the Thai Red Cross Society. So a high-THC extract made in Thailand needs this licence as well as meeting any GMP requirement.
What to do: before you sell flower or biomass to an extractor, ask to see their extract licence. Also ask for the GMP certificate, if any, of the facility that will process your crop. This shows whether your crop is going into a licensed, quality-controlled process.
Is cannabis flower an API?
Not in the narrow sense of one defined molecule. The accurate answer is that it depends on how the flower is used, and the GMP guides say so:
- ICH Q7 notes that the legal classification of a material as an API differs between countries. Where a material counts as an API in the country where it is made or used, it should be made according to ICH Q7.
- Annex 7 of the EU and PIC/S GMP guides covers herbal medicines and is more direct. The GMP classification of herbal material depends on how the manufacturing authorisation holder (the company licensed to make the medicine) uses it. The material may be classed as an active substance, an intermediate or a finished product.
In practice there are three common situations:
- Flower as the finished product. Dried flower dispensed to patients is the medicine itself. It is not an ingredient going into another medicine.
- Flower as a starting material. Flower that will be extracted is herbal material at the start of an API process or an intermediate process.
- Flower as the active substance of a herbal product. Cut or powdered herb can be the declared active substance. This applies where the product and the country’s rules treat it that way.
Annex 7 also has a table that shows where farming ends and GMP begins:
- Cultivation, collection and harvesting fall under GACP.
- Further cutting and drying fall under GMP.
Translator’s note: In Thailand, cannabis flower (ช่อดอกกัญชา) is a controlled herb. This comes from the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568. The notification was issued under the Thai Traditional Medicine Protection Act B.E. 2542 and has been in force since 26 June 2025. Flower may be sold only with a PT 33 (ภ.ท.33) prescription, for a maximum of 30 days. Advertising and online sale of flower are prohibited. The Ministerial Regulation on Controlled Herbs (No. 2) B.E. 2569, in force since 30 April 2026, tightens the licence criteria for cannabis flower.
Translator’s note: Flower dispensed on a PT 33 prescription is closest to situation 1 above. Ask your buyer and your licensing authority whether GMP or GACP applies to cutting and drying in your case. In either case, drying is a step where Thai heat and rainy-season humidity can damage quality. Drying at 85–95% humidity compares practical drying setups for Thai conditions.
What to do:
- Before you sign a supply deal, agree in writing which of the three roles your flower will play. This decides which standard your buyer will check you against.
- Keep full GACP records for cultivation and harvest. These are the steps Annex 7 places on the farm side.
- Include spray records. Use only pesticides registered with the Department of Agriculture (กรมวิชาการเกษตร), and only as the label directs.
- Record the temperature and humidity in your drying room every day. If a buyer later asks for GMP-level drying, this record shows how each batch was dried.
- Ask the buyer whether they want to do the cutting and drying in their own GMP facility.
Five common mistakes
- Calling any isolate an API. An isolate is a single cannabinoid purified out of the plant, such as CBD isolate. An isolate supplied for medicine manufacture is expected to be made under API GMP: EU or PIC/S Part II, based on ICH Q7. Purity alone does not make it an API.
- Treating excipients as unimportant. Excipients are part of the medicinal product. EU and PIC/S rules require manufacturers to control excipients and their suppliers. That control must rest on a formal quality risk assessment, which is a written review of what could go wrong with each excipient and how serious it would be.
- Assuming high-grade flower is automatically an API. Depending on its use, it may be a finished product, a starting material or an active substance.
- Mixing up the abbreviation. In pharmaceutical documents, API means active pharmaceutical ingredient. It does not mean application programming interface, the software term.
- Ignoring national classification. One country may treat a material as an API while another country regulates it differently.
Translator’s note: The last point matters most if you sell abroad. A material that is a finished product in Thailand may count as a starting material in the buyer’s country. The export pathway topic covers what overseas medical buyers usually check.
What to do: use these five points as a checklist whenever you read a buyer’s specification sheet or contract.
Who decides, and what to do next
The competent authority (the government body that regulates medicines) in the market you supply decides the classification, case by case. Check that authority’s current rules. If a material falls between two categories, ask the authority directly.
Translator’s note: Thai rules are still changing. The draft Cannabis Control Act is not law yet. The Cabinet approved the draft on 22 September 2026 and sent it to the House of Representatives. Until the draft becomes law, the notification and ministerial regulations described above still apply. Before you rely on any classification, ask the Thai authority that issues your licence.
Your next steps:
- For each buyer, write down what they will do with your flower. This tells you which of the three roles it plays.
- Ask each buyer which GMP guide they follow and at which step it starts. This shows where your responsibility ends.
- Keep GACP records for cultivation and harvest, including spray records and drying-room readings. These are what a medical buyer will audit.
- If your material falls between two categories, send a written question to the competent authority and keep the reply. A written answer protects you if the classification is questioned later.
Do you supply flower or biomass to a medical or extraction buyer? Share below this topic which records they asked you for, so other growers can see what real buyers require.
References
- ICH Q7: GMP guide for active pharmaceutical ingredients (definitions, scope, and table of API manufacturing steps).
- Directive 2001/83/EC (EU law on medicinal products for human use): definitions of active substance and excipient.
- EudraLex Volume 4, Part II: “Basic requirements for active substances used as starting materials”.
- PIC/S GMP Guide, Part II (based on ICH Q7, adopted by PIC/S in 2001).
- EU and PIC/S GMP Guides, Annex 7 (herbal medicinal products): classification of herbal material, and the boundary between GACP and GMP.
- US Food and Drug Administration: description of Epidiolex as containing a purified form of the drug substance CBD.
- European Pharmacopoeia: monographs “Cannabis flower” and “Cannabidiol isolated from Cannabis sativa L.” (implementation date 1 July 2024).
- Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568 (Thailand).
- Ministerial Regulation on Cannabis or Hemp Extracts B.E. 2569 (Thailand).
- Ministerial Regulation on Controlled Herbs (No. 2) B.E. 2569 (Thailand).