Temperature-sensitive pharmaceuticals may degrade if not stored and transported under strictly controlled environmental conditions, resulting in loss of therapeutic efficacy and, in extreme cases, a risk to patient health. Proper cargo-space temperature mapping is essential for GDP compliance.
Article originally available in ŚWIAT PRZEMYSŁU FARMACEUTYCZNEGO 2/2025
Authors: MSc Eng. Dorota Niedojadło, MSc Eng. Mateusz Głąb, MSc Eng. Bogdan Szczepański
Central Refrigeration Centre COCH in Kraków Sp. z o.o.
Temperature-sensitive pharmaceutical products, if not stored and transported under strictly defined environmental conditions, may degrade, resulting in loss of their therapeutic efficacy and, in extreme cases, may pose a risk to patient health. Therefore carriage and storage of these products requires maintenance of a precisely defined temperature range that ensures preservation of their quality and, consequently, the safety of their use and effectiveness of action.
Both national and international regulations impose on entrepreneurs trading in these products an obligation to observe specified rules, including performing temperature mapping in the case of transport by temperature-controlled vehicles.
The article presents basic information concerning means of transport, proposed test methods and the most common inconsistencies in reports from so-called temperature mapping of the cargo space.
Temperature mapping consists in documenting the temperature distribution in the cargo space, including indication of locations with the highest and lowest values – so-called critical points. Data collected during this process constitute the primary source of information necessary to ensure proper transport conditions for medicinal products within the required temperature range. The main goal of mapping is to detect temperature deviations in selected areas of the cargo space that may constitute a potential threat to the quality of the medicines carried.
According to the Regulation of the Minister of Health of 13 March 2015 on the requirements of Good Distribution Practice (GDP) (Journal of Laws 2022 item 1287) concerning medicinal products, temperature mapping in temperature-controlled vehicles should be performed under representative conditions taking into account seasonal temperature variations. This means the need to test vehicles under extreme conditions, e.g. −20°C for the winter season and +38°C for the summer season.
The regulation also imposes an obligation of regular maintenance and calibration of temperature monitoring equipment used during transport. This is aimed at ensuring measurement accuracy and maintaining appropriate storage conditions for medicinal products throughout the supply chain.
Analogous guidelines are found in the European Commission Guidelines of 5 November 2013 on good distribution practice of medicinal products for human use, which emphasise the importance of performing temperature mapping under representative conditions and the need for regular maintenance and calibration of temperature monitoring devices.
General principles for wholesale distributors supplying medicinal products contained in this document include responsibility for protecting these products against damage, counterfeiting and theft. Equally important is ensuring that during transport the temperature inside the cargo space is maintained within the allowable limits specified by the medicine manufacturer or indicated on the outer collective packaging.
It should also be documented that medicines were transported under conditions that did not negatively affect their quality and integrity. Any deviations that occurred during transport such as temperature fluctuations or damage should be reported both to the distributor and the recipient.
In connection with the above, in the case of transport of temperature-sensitive medicinal products, in order to ensure proper carriage conditions between manufacturer, wholesale distributor and customer, specialised means intended for this purpose should be used, such as thermal packaging, insulated containers or vehicles with a temperature control system.
Vehicles used for carriage of this type of specialised product must provide the ability to control and continuously monitor and maintain the required temperature values, and their equipment should be regularly checked, verified or calibrated, in a documented manner, in order to confirm correct operation and conformity with applicable requirements.
The regulation and EU guidelines do not, however, define a detailed methodology or conditions for temperature distribution tests, limiting themselves only to stating that they should be performed “under representative conditions”. Such a general formulation finds its justification due to the large diversity of products transported, temperature ranges and possible carriage route profiles.
The lack of clear guidelines concerning the methodology of temperature distribution testing, as well as insufficient supervision and control by the competent institutions, has in recent years led to the appearance on the market of many companies providing temperature mapping services whose quality often raises doubts and may mislead recipients of the reports.
The lack of requirements concerning conditions and methods of conducting tests, the form of reporting their results and the lack of supervision of these processes mean that these activities are often carried out omitting their basic goals. As a result they should not constitute a basis for confirming fulfilment of requirements, because they do not enable drawing reliable conclusions necessary for correct monitoring and planning of medicinal product transport.
In practice this means that such reports are not only useless but may also create a risk to the quality of the products carried. Examples of this type of inconsistency are presented later in this publication.
Requirements for means of transport
Temperature-controlled means of transport intended for transport of medicinal products are vehicles with thermally insulated bodies equipped with refrigeration-heating units. Requirements and technical standards for this type of means of transport – covering trucks, trailers, semi-trailers, vans and related refrigeration and heating systems – were originally developed mainly with transport of perishable foodstuffs in mind.
Maintaining high food quality requires preservation of specified insulation classes and precise temperature assurance. In connection with this, requirements regarding thermal insulation as well as refrigerating and heating capacity are very restrictive for food.
Although design and operation of vehicles intended for distribution of temperature-sensitive medicinal products is subject to additional criteria, there are no clear requirements concerning thermal insulation parameters and performance of cooling and heating systems. Nevertheless, according to the recommendations of many organisations, including the World Health Organization (WHO), it is recommended that means of transport used for carriage of temperature-sensitive products meet the requirements defined in the so-called ATP Agreement.
The ATP Agreement (Agreement on the International Carriage of Perishable Foodstuffs and on the Special Equipment to be Used for such Carriage) contains basic requirements and test procedures that may also be applied to assessment of means of transport used in logistics of medicinal products requiring controlled temperature.
A vehicle holding an ATP certificate meets requirements concerning insulation properties, defined by means of the overall heat transfer coefficient “K”. According to the rules, the value of this coefficient should not exceed:
- 0.4 W/m²K – for reinforced insulation (class IR),
- 0.7 W/m²K – for normal insulation (class IN).
Fig. 1. Specimen ATP certificate and markings according to the ATP Agreement, showing an example certificate, plate and FRC sticker.
This means that bodies with too high an overall heat transfer coefficient do not meet the requirements defined in the ATP Agreement. A lower value of the “K” coefficient translates into higher energy efficiency and ensures lower energy consumption by refrigeration or heating units, as well as longer maintenance of the required temperature in the cargo space in the event of failure of these systems.
Equally important, refrigeration units compliant with the ATP Agreement must undergo specialist performance tests at independent, authorised testing stations. These tests determine their performance for different temperature levels.
Depending on the insulation class of the body and the performance of the refrigeration or heating unit used, the set (i.e. thermally insulated body together with the thermal unit) may obtain an ATP certificate in the appropriate class, in accordance with the criteria contained in the ATP Agreement.
Test procedures, classification and marking of means of transport, as well as specimen certificates (Fig. 1) and test reports, are described in detail in the text of the ATP Agreement. This document is regularly updated by working group WP.11 on transport of perishable foodstuffs, operating within the United Nations Economic Commission for Europe (UNECE).
The ATP Agreement is generally available in three official languages: English, French and Russian. The latest version, in force from 22 June 2024, contains current requirements concerning means of transport for carriage of temperature-sensitive products.
The Polish language version of the ATP Agreement is published in the Journal of Laws – the currently applicable version is from 2020, announced in Journal of Laws 2022 item 1824.
As mentioned earlier, for transport of medicinal products more stringent requirements apply than those provided for foodstuffs covered by the ATP Agreement. For food, maximum allowable carriage temperatures are usually defined, whereas medicinal products require a strictly defined temperature range – with clearly defined minimum and maximum temperature – and the smallest possible temperature fluctuations during transport.
In connection with the above, a means of transport should:
- meet the requirements of the ATP Agreement or equivalent requirements by confirming insulation properties and performance of thermal units in accordance with applicable standards using reliable, accurate and reproducible measurements and calculations, using recognised and modern measurement methods for the required carriage temperature;
- maintain the required, often very narrow temperature range throughout the cargo space.
Fulfilment of this second requirement may be confirmed by performing a temperature distribution test (so-called temperature mapping), which enables assessment of the uniformity of temperature conditions inside the cargo space.
The temperature distribution at individual points and zones of the cargo space is influenced inter alia by:
- insulation properties of the body,
- presence of structural elements such as doors and ventilation openings,
- performance of refrigeration and heating units,
- air circulation and distribution system,
- temperature difference between the body interior and the surroundings,
- unit control parameters such as operating mode (continuous or intermittent), set temperature hysteresis, evaporator fan speed, and method and frequency of defrosting.
Test methods
Depending on circumstances, temperature mapping may be performed both with an empty cargo compartment and with a loaded compartment. If the cargo space is subject to seasonal temperature variations, tests should be performed separately for periods representing the hottest and coldest seasons. During mapping, refrigeration or heating unit set-points enabling maintenance of the required temperature ranges should be used.
For correct performance of mapping the following are essential:
- an appropriate number of temperature sensors of the required accuracy,
- specialist software enabling recording of the temperature distribution in the tested object, data archiving and analysis,
- regular calibration of measuring instruments to ensure metrological traceability, in order to confirm proper accuracy of the measurements performed.
EU GDP (Good Distribution Practice) guidelines, which require confirmation of the suitability of the means of transport for carriage of medicines in the required temperature range, do not specify the detailed scope or conditions for performing qualification tests. As a result of the lack of standardisation, some companies providing temperature mapping services have begun to create their own “procedures”. Unfortunately, they are often not supported by any applicable standards, analyses or use of reliable and reproducible measurement methods – and the only criterion for their selection is often only adaptation to the internal capabilities of the contractor.
Based on their experience, recognised organisations have developed their own procedures and guidelines that significantly raise the quality and reliability of qualifications performed. Of particular note are:
- DIN SPEC 91323 – a German technical specification, adopted as a standardised document by the Polish Committee for Standardization under the designation PKN-DIN SPEC 91323 (available in Polish),
- WHO guidelines concerning transport systems for temperature-sensitive products.
This article will discuss the requirements of DIN SPEC 91323, because this document has been introduced by the Polish Committee for Standardization as document PKN-DIN SPEC 91323. It was developed in response to the needs of manufacturers of refrigerated vehicles and the pharmaceutical industry and concerns vehicles with temperature-controlled cargo space. This document offers uniform and transparent test procedures that may constitute a basis for qualification of means of transport used for carriage of medicinal products.
DIN SPEC 91323 also takes into account WHO recommendations, according to which the qualification procedure should:
- demonstrate, based on documented tests under controlled conditions, that a temperature-controlled cargo compartment is able to maintain the required temperature range in the loading area, including under extreme ambient conditions expected during normal operation,
- confirm correct operation of the equipment or installation (e.g. refrigeration or refrigeration-heating unit) under real operating conditions,
- identify cargo zones where products should not be placed (e.g. near the evaporator or in areas of intense cold air flow),
- determine the time after which the temperature in the cargo space will exceed the allowed minimum or maximum in the event of failure of the temperature control system,
- include tests reproducing expected door opening times of the cargo compartment during deliveries,
- take into account other disturbances, including cycles, times and temperature deviations related to defrosting of refrigeration units.
Tests according to PKN-DIN SPEC 91323:2019-08
PKN-DIN SPEC 91323:2019-08 “Commercial vehicles with temperature-controlled cargo space used for distribution of pharmaceutical products (for human or veterinary use) – Guidelines for qualification” defines requirements for tests performed for functional qualification of commercial vehicles with temperature-controlled cargo space intended for distribution of pharmaceutical products within a specified temperature range.
As part of the qualification process the following documents in particular should be submitted:
- description of the structure of all walls and usable surfaces or a document confirming the value of the overall heat transfer coefficient K,
- technical specification of the cooling and heating unit together with confirmation of refrigerating and heating capacity (if available),
- for multi-temperature means of transport: temperature ranges in individual compartments, together with construction details and information on fixed or movable partitions (dividing walls),
- specification of the temperature recorder together with a calibration certificate; for temperature measurement systems used in vehicle qualification according to PKN-DIN SPEC 91323 a maximum allowable measurement error of 0.5 K applies, and calibration of each instrument should be performed at least once a year,
- instructions for cleaning the interior of the body,
- diagram of the refrigeration system and heating system,
- information and specifications concerning the air distribution system,
- operating instructions, in particular concerning the refrigeration and heating unit, temperature measurement devices and telematics systems (if installed),
- maintenance schedule for the refrigeration and heating unit.
Required ambient (external) temperatures were defined as applicable for the territory of Germany. A reservation was included, however, that when vehicles are used in other regions, local maximum and minimum temperatures should be taken as the basis for determining these temperatures.
Information concerning temperatures in Poland is contained in National Annex NA to PKN-DIN SPEC 91323:2019-08.
Table 1. External temperatures recommended during tests according to PKN-DIN SPEC 91323:2019-08
| External temperature: | Germany | Poland |
|---|---|---|
| maximum for the summer period | +38°C | +30°C |
| minimum for the winter period | −17°C | −20°C |
Table 2. Internal temperatures recommended during tests according to PKN-DIN SPEC 91323:2019-08
| Available ranges and notes |
|---|
| ≤ −20 °C |
| ≤ −15 °C |
| +2 to +8 °C |
| +8 to +15 °C |
| +15 to +25 °C |
| +2 to +30 °C |
| individually selected ranges |
| 1. At extreme external temperatures the limits of the carriage temperature range should be reached. |
| 2. Category A and B vehicles are tested in at least one temperature range. |
| 3. Qualification of multi-temperature vehicles is performed in parallel mode. |
Temperature outside the body should be measured at at least four locations distributed around the compartment, at a specified distance from its surface.
Test conditions and procedures depend on the following vehicle categories:
- Category A – vans (delivery vehicles),
- Category B – box trucks, trailers, semi-trailers.
Placement of measurement points inside the means of transport depends on the dimensions of the cargo compartments. Compartments of Category A and B vehicles are treated separately and within each of these categories they have been divided into two groups depending on the length of their cargo space.
A compartment of length L>2.35m
B compartment of length L≤6m
B compartment of length L>6m
A compartment of length L≤2.35 m
Table 3 Idle speeds and mean operating speeds according to DIN EN 16440-1: 2015-05
| Vehicle / engine type | Idle speed | Mean operating speed |
|---|---|---|
| Trucks, diesel engine < 240 kW | 800 min⁻¹ | 1300 min⁻¹ |
| Trucks, diesel engine ≥ 240 kW | 800 min⁻¹ | 1700 min⁻¹ |
| Light trucks, diesel engine | 800 min⁻¹ | 2200 min⁻¹ |
| Light trucks, petrol engine | 800 min⁻¹ | 3300 min⁻¹ |
| *) For vehicles with elevated idle speed (> 800 min⁻¹), the actual rotational speed is established as speed 1. | ||
Example vehicle test programme under summer conditions – cooling mode
The preliminary stage is preparing the vehicle for tests under appropriate environmental conditions. The vehicle with open cargo compartment doors, equipped with a complete temperature measurement system, is placed in the test chamber and exposed to the external temperature, e.g. +38°C, in order to equalise the temperature of the compartment walls throughout the volume with the ambient temperature. Temperature equalisation time should be at least 6 h. After temperature equalisation the body doors are closed and the refrigeration unit is started with the appropriate temperature set-point. This is the start of the cooling phase.
The cooling phase ends when the readings of all internal temperature measurement sensors are within the required temperature range.
After obtaining the set temperatures, one should proceed to the next phase of steady state and checking the defrost system. It lasts at least 2 h within the range controlled by the temperature controller. If the test is performed for carriage temperatures in the range 2°C to 8°C or lower, after 2 h of testing a defrost process should be carried out, after which the test should be continued for a further 2 h.
The final stage of tests includes simulation of disturbances and failures; this stage includes a test of the effect of opening the body doors and simulation of unit failure by switching it off.
Testing of the vehicle under winter conditions – heating mode – is performed in an analogous manner.
Criteria for assessing test results
- Test in cooling and/or heating mode: The result is positive if, during the final 2 hours of steady state, temperatures at all measurement points remain within the required range.
- Simulation of equipment disturbances and failures: Results of disturbance simulation tests are considered positive if, after restarting the equipment, the temperatures inside the body achieved during steady state are restored. Results of failure simulation tests are very helpful and recommended when planning measures to protect the cargo should such a situation occur.
Most common inconsistencies and errors in mapping reports
- Lack of information or very general information concerning placement of measurement sensors in practice prevents identification of the hottest and coldest points/zones, which is essentially the primary goal of the test. For example, insufficiently detailed descriptions and/or diagrams are used. Reports lack information on temperatures recorded at individual sensors, and only poorly readable charts and general summary information are included, e.g. that “during the temperature distribution test temperature stability was very high for all measurement points”. Example 1: “Sensors were placed so that they could record the location with the most unfavourable temperature values. Measurement points were placed in locations exposed to the greatest temperature fluctuations – on specially constructed stands and were distributed at three height levels approx. 20 cm, approx. 120 cm, approx. 240 cm from the floor”
Example 2: “For a cargo space oscillating around 10–20 m³ it was assumed that use of 10–20 sensors for measurements is indicated. The tested vehicle has one compartment (with partition capability), which gives a total of 16 sensors.”
The adopted test methodology is not precise; the wording is very general. The entity performing the tests did not justify why for a cargo space oscillating around 10–20 m³ it was assumed that use of 10–20 sensors for measurements is indicated. Lack of reference to any standards, specifications or technical specifications on the basis of which the number of measurement points is selected. - Lack of information on the external temperature at which the check was performed, or performing tests at a temperature outside the body close to the required carriage temperature range. For example: performing mapping for the range 15÷25°C at external (ambient) temperature +20°C, which does not reflect real, more demanding conditions.
- Referring to test methods based on legal acts or guidelines issued by recognised institutions in order to lend credibility to the measurement method applied, even though none of these documents indicates a specific test method. Frequently cited are: the Regulation of the Minister of Health on Good Distribution Practice, WHO guidelines and Directive 2001/83/EC of the European Parliament and of the Council of 6 November 2001.Quote from an example report: “MAPPING METHOD: Mapping was performed in accordance with the ‘Procedure for mapping temperature distribution of refrigerated semi-trailer XXX’ according to the Regulation of the Minister of Health of 13 March 2015 on the requirements of Good Distribution Practice based on Article 97 of the Act of 6 September 2001 and WHO requirements for Good Distribution Practices defined as a quality management system extending from shipment of the product from the plant to the target customer and based on Directive 2001/83/EC.”
- Failure to take into account or omitting defrost periods, which in practice will certainly occur e.g. during tests in the carriage temperature range of 2÷8°C, and which affect the temperature inside the compartment.
- Excessively long intervals between readings, which means that even multi-minute defrost periods may not be recorded and may be omitted. Furthermore, especially with smaller refrigeration units, when continuous operation mode consists of continuous fan operation while the compressor cyclically switches off after reaching the set temperature, this may lead to momentary temperature exceedances in the cargo compartment that may also go unnoticed.
- Lack of confirmation of metrological traceability of measuring instruments (thermometers, temperature sensors, data loggers, etc.) used to perform the temperature distribution test (e.g. through accredited calibration certificates of instruments) and use of inappropriate measuring instruments. Using instruments of insufficient accuracy, as well as not taking measurement errors into account.For example: using temperature sensors with an error of 1°C and a data logger with an error of 1°C and not taking this into account in measurement results means that an obtained reading of 2°C is actually 0°C (risk of freezing the cargo).
- Lack of simulation of disturbances such as unit failure, door opening, which means that if they occur the planned protective measures may prove ineffective.
- Resolution and scaling of included charts preventing precise reading of data.
- Adapting the test method to the company’s capabilities, e.g. reducing or limiting the number of measurement points in the case of lack of an appropriate amount of measuring equipment or its failure.Example from a report: “During mapping sensors No. XXXX, No. YYYY failed. Without effect on the test result”.
In the case of inability to record two measurement points it would be indicated to repeat the test. It is doubtful on what basis the contractor concluded that eliminating two sensors (failure) did not affect the test result.
Test report
Analysing GDP requirements developed by recognised institutions and generally accepted principles of reporting test results, such as those resulting from PN-EN ISO/IEC 17025:2018-02, the protocol should contain at least the following data:
- title, name and address of the laboratory,
- place of performance of the activity,
- unique identification ensuring that all elements of the protocol form part of a complete report, together with unique identification of its end,
- name and contact data of the client,
- identification of the method applied together with its description,
- unique identification of the tested object and, if necessary, its condition,
- date of receipt of the object(s) for testing (if relevant to the validity of the results and their application),
- date(s) of performance of the activity,
- date of issue of the report,
- statement that the results relate only to the objects tested,
- results together with appropriate units of measurement,
- additions, deviations or limitations of the method applied,
- identification of the person (or persons) authorising the report,
- scope of tests, including detailed information enabling accurate analysis of the data obtained, such as:
- ✓ placement of temperature sensors both inside and outside the body,
- ✓ temperature set-points on the unit controller,
- ✓ operating conditions of the refrigeration or refrigeration-heating unit (e.g. type of compressor drive and rotational speed),
- ✓ for tests of a loaded body – type and method of cargo placement.
For multi-compartment bodies of means of transport having two or more insulated compartments intended to maintain different temperature ranges, the report should contain appropriate data concerning each of the compartments. Additionally, for multi-compartment means of transport having two or more insulated compartments intended to maintain different temperatures in each of them, the positions of the partition wall(s) and temperature set-points in the individual compartments should be indicated.
Summary
The requirement to map the cargo space of means of transport is aimed at maintaining high quality of the medicines carried. A mapping report should constitute a reliable source of information for all participants in the medicine distribution chain – from the production stage through logistics to the end customer. Correctly performed temperature mapping constitutes a solid basis for protecting costly cargo and preventing loss of properties of the medicines carried, which may have a direct impact on human health and life.
Currently, due to the lack of verification of test quality, the mere existence of a document called a mapping report is often considered sufficient, which unfortunately gives permission for this service to be performed by incompetent contractors. As a result, equipment that does not meet GDP requirements and poses a risk to the cargo carried may be used for medicine transport.
Use of the test methodology presented in this article may significantly help introduce and apply uniform criteria for testing and certification of means for transport of temperature-sensitive medicinal products by different testing laboratories and certification bodies.
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