Level A, B and C in non-sterile compounding

By Dumitru Musteata, RPh, Pharmacy Compounding Compliance. Last reviewed October 1, 2026.

This guide is independent commentary. It has not been reviewed, approved or endorsed by NAPRA or by any pharmacy regulatory authority, and the interpretations in it are the author’s own, not NAPRA’s. Your provincial or territorial regulator sets the requirements that apply to your pharmacy. They may or may not be based on NAPRA’s model documents and can differ between provinces, so always check your regulator’s current documents.

The Model Standards for Pharmacy Compounding of Non-Sterile Preparations sort compounding into three levels of requirements. A level is not a label attached to a drug. It is the result of a risk assessment, and it determines the space, equipment and precautions a pharmacy needs before it makes a preparation.

The three levels at a glance

Level A

For simple and moderate preparations. It requires a designated, separate compounding area and the general requirements for procedures and equipment. Simple or moderate preparations that contain certain hazardous drugs or WHMIS health hazards can be made at Level A when they are compounded in occasional small quantities, the risk assessment finds little or no risk to personnel, and appropriate precautions are taken.

Level B

For complex preparations, and for small quantities of ingredients that require ventilation. In addition to the Level A requirements, it requires a dedicated room separate from the rest of the pharmacy, which gives more work space, storage, uninterrupted workflow and protection from cross-contamination. A ventilated, entirely closed-off room, or a room with a ventilated containment device, is required for certain powders, aromatic products and other hazardous products, including allergenic products and products that could have unintended effects, such as hormones, when they are prepared in small quantities and the risk can be mitigated.

Level C

For hazardous drugs that the standards identify with NIOSH Group 1, for materials that WHMIS classifies as health hazards such as those very irritating to the respiratory tract, skin or mucous membranes, and, depending on the risk assessment, for other NIOSH-listed drugs when large quantities of active ingredient are used routinely. It requires a physically separate room that is externally ventilated through HEPA filtration, with appropriate air exchange and negative pressure relative to the surrounding rooms, an appropriate containment device and protective equipment for handling hazardous products. The guidance document (section 9.1.1), repeated in Ontario’s assessment criteria, says the room should have at least 12 air changes per hour and negative pressure of 2.5 Pa relative to surrounding areas.

Simple, moderate and complex

The levels lean on three categories of complexity, taken from an earlier edition of USP General Chapter <795>:

  • Simple: the preparation has a USP compounding monograph, or appears in a peer-reviewed journal article with specific quantities, procedure, equipment and stability data with a beyond-use date.
  • Moderate: it requires special calculations or procedures, or stability data for that specific formulation are not available.
  • Complex: it requires special training, environment, facilities, equipment and procedures. Examples include transdermal dosage forms, modified-release preparations and some inserts and suppositories for systemic effects.

How the decision algorithm works

The guidance document includes a decision algorithm (Diagram 1 in section 4.2). In words:

  1. Is an ingredient in the first NIOSH table? If yes, ask whether it is an occasional small quantity. If it is not, the answer is Level C. If it is, ask whether the ingredients require greater precautions to protect the patient or personnel. If they do, Level B. If they do not, the level follows complexity: simple or moderate is Level A, complex is Level B.
  2. If not, is an ingredient elsewhere on the NIOSH list, or a health hazard under the Hazardous Products Act? If no, the level follows complexity: simple or moderate is Level A, complex is Level B.
  3. If yes, does the NIOSH or WHMIS information say the material requires ventilation, or is it a reproductive risk to the compounder? If yes, go to the occasional small quantity question in step 1. If no, go to the greater precautions question in step 1.

The algorithm was drawn when the NIOSH list had three groups. The 2024 list has two tables with different criteria, so the first question needs care. NIOSH 2024, WHMIS and “occasional small quantity”

Ventilation by level

The Ontario College summarizes the external ventilation requirements this way:

  • Level A: external ventilation is not required for the designated compounding area.
  • Level B: external ventilation is not required for the room, but the room must be entirely closed off from the rest of the pharmacy and well ventilated. If a containment device is installed, it should be externally vented, which is preferred, or have redundant HEPA filters in series.
  • Level C: the room must be separate, under negative pressure and have appropriate air exchange, with external ventilation through HEPA filtration. The containment device should be externally vented or have redundant HEPA filters in series.

“External” means the air leaves the building, not just the room.

Why there is no list of Level A, B and C preparations

Regulators are asked for one regularly, and the Ontario College’s answer is no: the standards do not assign specific drugs, ingredients or formulations to a level. The same formulation can be assessed differently in two pharmacies because quantities, frequency, the size and layout of the pharmacy, the staff and the ways risk can be mitigated all differ.

The College’s own worked examples show the spread. Hydrocortisone powder in clotrimazole cream, 30 g made every two months, is assessed at Level A. Progesterone 400 mg suppositories made weekly in batches of 60 are assessed at Level C. The guidance document gives a third illustration: a simple preparation containing a NIOSH-listed drug such as clonazepam or carbamazepine could be compounded at Level A, provided the quantity is small and the drug’s physical characteristics limit contamination and risk to personnel.

Cumulative risk

An occasional small quantity cannot be judged in isolation. The supervisor has to consider the combined risk of everything the pharmacy compounds, even on different days. A pharmacy that makes many different hazardous preparations occasionally can end up needing the same level of requirements as one that makes a few routinely.

When the preparation needs more than your space provides

If a preparation needs processes or safety measures the pharmacy does not have, the documentation should set out the risks, the extra steps taken to mitigate them, and references confirming that those steps work. The guidance document also lists the other honest answer among its questions for deciding whether to compound at all: refer the preparation to a pharmacy with the appropriate facilities, equipment and expertise. Where the level is uncertain, both the Ontario and Alberta colleges direct pharmacies to the higher standard.

Will the levels change?

NAPRA’s 2026 consultation draft of new non-sterile compounding standards kept Level A, B and C. It is a draft and may change, and each regulator will decide how to use the final version. Where the draft stands

Sources

Need the level documented for each preparation?

That is what a risk assessment is for. We prepare one for every preparation you compound, with the reasoning written down for your supervisor to review. About the risk assessment service

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