Defining time critical medicines

Value of a definition

Understanding what characteristics define whether a dose of a medicine is time critical can support safe prioritisation of medication-related clinical decisions, patient pathways and processes.

There is no universally agreed definition of time critical medicines (TCMs). This adds to the complexity of improving the safe use of these medicines. Some medicines, when used in specific clinical situations or patient groups, are more likely to cause harm if they are not taken at their intended timepoint.

One definition of TCMs used by the Institute for Safe Medication Practices Acute Care Guidelines in the USA defines time critical medicines as ‘those where early or delayed administration of maintenance doses of greater than 30 minutes before or after the scheduled dose may cause harm or result in substantial sub-optimal therapy’.

Using a definition for quality improvement

When undertaking TCMs quality improvement work a locally agreed definition of TCMs will be necessary to measure improvement.

Time critical characteristics

There are a number of factors which influence whether a dose of medication could be considered time critical. The determination of a medicine’s time-critical nature is influenced by multiple clinical and contextual factors and must be assessed through professional clinical judgment.

Medication characteristics

The pharmacokinetics of a medicine can influence its time-critical nature. For example, medicines with a short half-life (such as short-acting insulin or levodopa) lose their effect quickly, increasing the risk of suboptimal therapy if doses are delayed.

The route of administration can affect time sensitivity. For instance, a long-acting depot injection has different urgency compared with an intravenous medicine.

Clinical indication

Treatments for specific conditions may be considered time critical as sub-optimal therapy may lead to immediate clinical risks, long-term clinical complications or a deterioration of the individuals functional status. Examples include:

• anti-seizure medicines for a person with epilepsy
• Parkinson’s therapy used to control movement disorder
• insulin in people living with diabetes

Clinical status

An individualised clinical judgment based on the individual’s condition and clinical scenario will influence whether a dose of medicine is time critical. A dose of medicine may be considered time critical if a delay could contribute to rapid further deterioration and harm, for example:

• adrenaline for the treatment of severe anaphylaxis
• hydrocortisone for the treatment of adrenal crisis
• rasburicase for the treatment of Tumour Lysis Syndrome

Patient perception

Each individual will have their own perception of their medicines and may experience anxiety about the timing of their medicines. While a healthcare professional (HCP) may not consider a medicine to be time critical, for that patient it may feel highly significant. A patient centred approach must be considered.

Interpreting time critical characteristics

Any specific medicine can be influenced by these characteristics to change the time critical nature of the medicine, for example

• amiodarone is time critical in cardiac resuscitation, but less time critical when used as an oral maintenance dosage for atrial fibrillation
• aspirin is time critical for the management of acute stroke, but less time critical when used as secondary prevention

List of time critical medicines

The value of creating a TCMs list is widely debated and should be considered on a case-by-case basis by individual organisations. There is no nationally agreed list of TCMs.

Value of a list

• Clinical healthcare professionals may use a list to help assess the time critical nature of a medicine and to prioritise processes for that medicine.
• A list may be a useful tool to support technical staff in making process-driven decisions related to medicine supply.
• A list may be used within training packages or for use by staff working in training posts.
• Medication safety initiatives may include a list as a tool to support quality improvement measurements.

Limitations of a list

• Individualised patient-centred clinical assessment is required to effectively assess the time critical nature; a list is not a substitute for individualised clinical assessment of a scenario.
• A list based solely on the type of medication may not factor in the clinical indication or clinical status. Medicines are used for multiple indications, not all of which are time critical.
• It is a challenge to reflect the operational steps necessary to ensure safe and timely administration.
• When a list is too long it creates a barrier to effective use and a reluctance among frontline staff, often under time pressures, to use it.
• A list is only of value if HCPs can access it at the point of care.

Setting-specific lists

A list may have more value when it is specific to a clinical setting, patient group or clinical scenario.

An example where a tool has been created using a defined list in a specific clinical setting is the Royal College of Emergency Medicine’s TCM safety flash. This provides a suggested list of some TCMs and important actions for HCPs working in emergency departments.

Using a list

Although no longer an active patient safety alert, the 2010 National Patient Safety Agency alert Reducing harm from omitted and delayed medicines in hospital included an action to identify a list of critical medicines and organisations may continue to hold this list.

Organisations are encouraged to review the value of having a list within their local services and how this contributes to the local strategies to improve the use of TCMs. Our article Improving the safe use of time critical medicines (SPS page) describes tools to implement improvement interventions.