Prescription Refills, Intervals and Part-Fills

A fact sheet is a plain-language explanation of the legislation that forms the foundation of certain pharmacy practices. It provides useful information and references to help pharmacy professionals understand a particular topic. A fact sheet is an informational resource and is not considered legal advice. Always refer to the legislation for full context. 

Legislative References 

• Controlled Drugs and Substances Act, 1996  
  • Controlled Substances Regulations  
• Drug and Pharmacies Regulation Act, 1990  
• Drug Interchangeability and Dispensing Fee Act, 1990  
  • R.R.O. 1990, Reg. 936: NOTICE TO PATIENTS 
• Food and Drug Act, 1985  
  • Food and Drug Regulations  

Additional References 

• Controlled Substances: Prescription Regulation Summary Chart 

Definitions 

Controlled substance: A substance set out in Schedules I, II, III, IV, or Part 1 of V of the federal Controlled Drug and Substances Act, 1996 (CDSA). Where applicable, this resource applies to the substances named in Schedule 1 (narcotics), Schedule 2 (controlled drugs) and Schedule 3 (targeted substances) under the Controlled Substances Regulations. 

Refills 

Prescription refills are not explicitly defined in legislation; however, federal regulations state that refills may be authorized on prescriptions for: 

• Prescription drugs (Food and Drug Regulations, C.01.042) 
• Narcotics, controlled drugs, or targeted substances (Controlled Substance Regulations, s 113, 117) 
  • Pharmacy professionals must record “the number of times that the prescription may be refilled and, if specified, the intervals between refills.” 

A prescriber can indicate on a written or verbal prescription whether they authorize it to be refilled and, if so, the number of authorized refills. 

• This includes when a pharmacist is prescribing (initiating, adapting or renewing a prescription). 
• The dispensing record for refills needs to be referenced to the original prescription that authorized them in an auditable and traceable manner. 

In situations where there are refills remaining on a prescription and a new prescription is issued, it is important to keep these prescriptions as separate authorizations and not simply add the newly authorized quantity to the existing prescription. Options include: 

• Continue to dispense the patient’s existing refills. 
  • The patient can retain the new prescription, or the pharmacy can retain it in the patient’s file (i.e., put on hold, logged, unfilled) for future use (even though the prescription still belongs to the patient until it is dispensed). 
• Discontinue or inactivate the patient’s existing refills and dispense the new prescription. 
  • Documentation of the pharmacist’s assessment, discussion with the patient, and rationale for the decision is important. 
  • Collaboration with prescribers is encouraged to understand their intent. 

Intervals 

Intervals between refills or part-fills (see below) are not required. If a prescriber chooses to include them, they may indicate either the number of days between, or dates, when the refills or part-fills may be dispensed: 

• If an interval is specified, the next refill or part-fill may be dispensed once the time frame indicated has elapsed. 
• Note that when an interval is equal to the number of days the prescription is expected to last, this means the prescription will be depleted before the next refill or part-fill is dispensed. 
  • Pharmacy professionals should consider the potential implications to continuity of care, if the patient runs out of medication and the pharmacy is closed on the day they are due. 
  • Collaboration with prescribers is encouraged to understand their intent and the desired outcome of specifying intervals. 
• If a patient requests an early refill or part-fill before the interval has elapsed: 
  • The pharmacist may use their professional judgment to dispense some or all of the next refill or part-fill 
  • The prescriber may be contacted for authorization, or notified of the early release 
  • Patterns of early refills should be monitored (e.g., for compliance, possible sharing or diversion of medication, inaccurate calculation of a day’s supply, miscounted prescriptions, accumulation of medication)
  • The pharmacist’s decision and rationale must be documented. 

Part-Fills 

Any prescription may be dispensed as a part-fill, described as dispensing a quantity of drug which is less than the total amount authorized by a prescriber. 

Part-filling may occur for several reasons: 

• The prescriber directs it when issuing the prescription, such as by specifying the quantity to dispense or a quantity that can be calculated from the prescribed dosage and duration. 
• The patient or their agent requests it, as Drug Interchangeability and Dispensing Fee Act (DIDFA), s 9, states that a pharmacy professional “shall dispense the entire quantity of the drug prescribed at one time…unless the person presenting the prescription in writing authorizes the dispensing of the drug in smaller quantities.” 
• It is required under R.R.O. 1990, Reg. 936, s 3 of DIDFA, when: 
  • A patient’s insurance plan (private or public) limits the quantity or duration eligible for coverage; or 
  • The pharmacist determines based on their professional judgment that dispensing a smaller quantity is necessary and in the patient’s best interest. 

When dispensing a lesser quantity is based on professional judgment, documentation of the pharmacist’s assessment, discussion with the patient, and rationale for the decision is important. For example, some reasons to part-fill may include: 

• facilitating compliance monitoring 
• assessing the effects of a new therapy 
• dealing with a drug supply issue (short expiry date, drug shortage or discontinuation) 
• tapering or de-prescribing 
• minimizing risk of diversion, loss or theft 

Patients should also be informed of any additional costs associated with part-fills (e.g., dispensing fee applies to each fill, and any copayment or deductible considerations). 

Additional Considerations 

• When a prescription is part-filled more than once, the quantity dispensed each time may vary. 
• Part-filling is not the same as creating a “balance owing”, an operational process used when there is insufficient medication inventory on hand. 
  • The patient should be presented with options to manage this situation and involved in making this decision 
  • The pharmacy dispenses a partial quantity of the prescription, based on the amount of medication immediately available, and anticipates the remaining quantity outstanding being procured and dispensed soon thereafter. 
  • The dispensing record needs to accurately reflect the quantities and dates for each portion dispensed. 
• If requested by a patient, the decision to dispense more than the quantity prescribed (but not more than the total authorized quantity) should be made considering any risks to the patient (e.g., challenges in monitoring therapy and compliance, stability of medication) and, ideally, in collaboration with the prescriber. 

Published: October 2026
Version #: 3.0 

Revision History 

Version #	Date	Action
1	March 2012	Published as “Narcotic Prescription Part-Fills”
1.1	March 2020	Added temporary CDSA exemption information
2	October 2021	Changed title to “Prescription Refills, Part-Fills and Intervals” Revised to include all federal drug schedules
3.0	October 2026	Updated to align with Controlled Substances Regulations; new content on other scenarios added