Quality Assurance in the medicinal plant production systems

Author: Zsuzsanna Pluhár

Introduction

 

 

Global and national markets for medicinal herbs have been growing rapidly in the last decades, and significant economic gains are being realized. The safety and the quality of the herbal medicines have become increasingly important for health authorities and the public as well. Some reported adverse events following the use of certain herbal medicines have been associated with the insufficient quality control of the raw materials.

The quality and safety of raw medicinal plant materials and finished products depend on factors that may be classified as intrinsic (genetic) or extrinsic (environment, collection methods, cultivation, harvest, post harvest processing, transport and storage practices). Contamination by microbial or chemical agents during stages of production can also lead to deterioration of safety and quality. Medicinal plants collected from the wild population may induce regional or local over-harvesting and protection of endangered species. The impact of cultivation or collection on the environment and ecological processes and the welfare of the local communities should also be considered.

In order to overcome the problems mentioned, quality assurance measures are needed to ensure a steady, affordable and sustainable supply of medicinal plant materials of good quality. Good agricultural practices have been recognized as an important tool for quality assurance of food commodities, however, herbal medicines are considered as more demanding than food production.

As a result of international (WHO: World Health Organization) and European (ESCOP: European Cooperative on Phytotherapy) efforts made on developing guidelines, focusing on the production and processing of medicinal and aromatic plants, a collection of directives have been established, which provides guidance on obtaining medicinal plant materials of good quality by the methods of sustainable production systems.

Basic terms

 

 

In general, quality is the combined characteristics of a product, making it suitable to meet the expected requirements. The definition of quality is associated with natural, economic and social concerns and can be approached by the different stages of production (raw material, finished product, etc.) or service involved. Different quality requirements are formulated depending on the type of utilization of the final product or the expectation of the consumers. The demands may change in the course of time, as a consequence of discovering new bioactive compounds or further type of application, therefore quality standards are to be improved progressively. This may have influence on several stages of the production line, too.

During quality control, certain characteristics of the product are compared to specific standards. Pharmacopoeial specifications have primary importance in the case of drugs and certain preparations of medicinal plants. In the course of drug quality control, drugs are subjected to a detailed examination according to the values specified in the respective standards of the official community (Ph. Eur.) or national Pharmacopoeias (Pharmacopoeia Hungarica 8th Ed., 2004). ConcerningThymi herba, requirements of the Ph. Hg. 8 are available at http://www.ogyi.hu/dynamic/Thymi_herba.pdf.

In order to assure the quality, a continuous attention is paid to measures influencing product quality during production processes, taking into consideration its conformity with standards. Quality can be assured on the basis of accurate measurements, observations and documentation of measures and circumstances.

If the product value is in accordance with the respective standards, which were proven by quality control (e.g. Pharmacopoeial), quality certification can be issued on adequate quality.

Prerequisites of quality assurance:

  • All the measures have to be planned in advance and made according to written instructions
  • Monitoring is obligatory before, during and after production
  • Continuous and retrievable documentation of all the processe

Quality assurance systems applied in medicinal plant production and processing

World Health Organization (WHO) has developed a series of technical guidelines on Good Agricultural and Collection Practices (GACP), relating to the quality control of the herbal medicines. The guidelines provide a detailed description of the techniques and measures required for the appropriate cultivation and collection of medicinal plants for the recording and documentation of necessary data and information during their processing.

The entire process of production of herbal medicines, from raw material to finished herbal products, was reviewed. WHO gave high priority to the development of globally applicable guidelines to promote the safety and quality of medicinal plant materials through the formulation of codes for good agricultural practices GAP (Good Agricultural Practice) and good collection practices of medicinal plants.

Despite such guidelines, there is still a disparity between knowledge and implementation: while pharmaceutical and other companies are striving to meet the requirements for the quality control, they cannot force farmers, producers and processors to follow the GACP. The training of relevant persons is therefore one of the key measures to be taken to ensure the implementation of quality assurance systems in the medicinal plant sector on national level.

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Newsletter of Global GAP (Source :http://www.globalgap.org)

WHO Guidelines on GACP (Good Agricultural and Collection Practice) is the improved version of GAP generalized for collection of medicinal plants, including measures of growing, collection and post harvest (WHO Guidelines).The objective of guidelines is to provide general technical guidance on obtaining materials of good quality for the sustainable production of herbal products classified as medicines. As a next step, national and regional guidelines should be developed: actually only the European Union, China and Japan possess special guidelines developed for this sector. In the EU, GACP was acknowledged by EUROPAM (the European Herb Growers Association GAP/GWP Subcommittee).

Concerning secondary processing of herbal drugs, guidelines of Good Manufacturing Practice have been implemented and followed. Standards and directives developed and published by ISO (International Organization of Standardization) have to be also considered in the course of manufacturing of drugs and medicinal plant products. ISO 9002 (standards related to quality management of technologies) and ISO 14000 (standards related to environmental management and safety) systems have already been implemented worldwide in the medicinal plant producing sector, especially in the fields of processing technologies of drugs and manufacturing the finished products.

The most important general guidelines of GACP, which have to be taken into consideration by the professionals of the medicinal plant producing and processing companies, are presented below.

Selection and botanical identification of cultivated medicinal plants

 In the medicinal plant growing practice, the first step is the selection of a medicinal plant species and variety, recommended by the national pharmacopoeia or other authoritative documents of the end-user country.

The botanical identity -scientific name: genus, species, subspecies, variety, author, family – of each medicinal plant under cultivation should be verified and recorded. Other relevant information, such as common name, cultivar name, ecotype, phenotype, chemotype and landrace may also be provided, as appropriate.

In the case of doubt concerning the identity, voucher herbarium specimen should be submitted to a regional or national herbarium. Documentation of the botanical identity should be included in the registration file.

Seeds and other propagation materials

 Supplier of seeds and other propagation materials should be specified. All necessary information relating to the identity, quality and performance of their products, as well as their breeding history should be provided by the supplier, if possible.

The quality of propagation material should be appropriate and free of contamination or diseases in order to promote healthy plant growth. Resistance or tolerance to biotic and abiotic factors is also preferable. Seeds used for organic production should be certified. Propagation material including genetically modified germplasm should comply with the national/regional regulations and be labelled and documented as required. Adulterated, substandard or excluded propagation materials must be avoided.

Guidelines on cultivation

General aspects

 Cultivation of medicinal plants requires intensive care and management. The conditions and duration of growing the required vary depending on the quality demands of medicinal plant material. Introduction into the culture or research of new crops is necessary, followed by the development of new technology and cultivation methods. Crop rotation and sustainable land use are preferred and environmental aspects should always be considered.

Site selection

 Average values of day length, precipitation, duration of sunlight, temperature should be considered and compared to the ecological demand of the medicinal plant prior to cultivation. Differences occur in quality of medicinal and aromatic crops, if cultivated in different growing sites, owing to the influence of the environment. These differences may relate to the physical appearance or to variations of their chemical constituents, which may be affected by the environmental factors.

Risk of contaminations as a result of pollution of air, soil or water by chemicals should be avoided. The impact of past land uses (previous crops, chemicals) should be evaluated, either.

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Peppermint field in the northern part of Vojvodina Province, Serbia (Photo: Pluhár, 2012)

 

Ecological environment and social impact

 The cultivation may affect the environment by changing its genetic diversity, ecological balance, especially when growing non-indigenous medicinal plants. The living organisms of the surrounding lands affect the growing, too. Thus, the ecological impact of cultivation should be monitored over the time, where practical.

The social impact of cultivation on local communities should also be examined and negative impacts should be avoided, while benefits - fair wages, local incomes of small or large scale cultivation/processing- should be provided, as much as possible.

Soil properties

The soil of the growing site should contain appropriate amounts of nutrients, organic matter and other element to ensure optimal growth. Soil type, drainage, fertility and pH all affect the quality parameters of the medicinal plant cultivated. Correct type and quantity of fertilizers should be applied, after soil evaluation and animal manure of documented origin is needed in proper quality.

Irrigation and drainage

 Irrigation and drainage should be controlled in accordance with the needs of the medicinal plant cultivated during growing and efficient amount of water should be used. Proper irrigation techniques are chosen to maintain plant health, especially in the case of the possibility of vector-borne disease transmission.

Plant maintenance and protection

 The growth and development characteristic of a species and the used plant part determine the management practices. Growth regulations by pruning, topping, shading, etc. are applied to improve the quantity and quality of the material produced.

Any agrochemicals used to promote growth and to protect medicinal plants should be kept to a minimum and applied when no alternative measures are available. Integrated pest management should be followed where appropriate by approved pesticides at the minimum effective level. Only qualified staff using approved equipment should carry out pesticide and herbicide applications and all the applications are to be documented. The minimum interval between treatments and harvest should be consistent with the labelling and instructions of the product. Growers should comply with the minimum residue limits (Codex Alimentarius, International Plant Protection Convention) considered by national authorities of the countries both of the grower and the end-user.

Guidelines on harvest

 Medicinal plants should be harvested during the optimal season and time period to ensure the best possible quality. The time of harvest depends on plant parts used and the concentration of active compounds varies with their developmental stages. Detailed information on timing of harvest is available in national pharmacopoeias, published standards, official monographs and major reference books. The best time for harvest (quality peak season/time of day) should be determined according to the quality and quantity of active constituents rather than the total vegetative yield.

During harvest we should make sure that no other materials, weeds and toxic plants are mixed with the harvested medicinal plant. Medicinal plants should be harvested under the best possible conditions, avoiding dew, rain and high humidity or immediately transported to dry place to prevent high moisture content promoting microbial fermentation and mould.

Cutting devices, harvesters and other machines should be kept clean and adjusted to reduce damage and contamination from soil (microbial load) or other materials. Harvested material should be transported promptly in clean and dry conditions to the processing facility, placed in clean baskets, dry sacs, tailers, or other well aerated containers. Harvesting machines and containers should be kept under clean and dry conditions in an area protected from insects and other animals.

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Insect trap applied in the depo of the processing plant of Herbária in Balmazújváros, Hungary (Photo: Pluhár, 2011)

Personnel in cultivation

 Growers and producers should have adequate knowledge of the medicinal plants concerned (botanical identification, cultivation characteristics, environmental requirements, harvest and storage). Personnel should receive training concerning measures of cultivation and processing and field workers should maintain appropriate personal hygiene. Properly trained personnel wearing appropriate protecting clothing (gloves, face masks, overalls, helmet, and goggles) should apply agrochemicals. Growers and producers should receive instructions concerning environmental protection and proper agricultural stewardship as well.

Post harvest processing

 Raw medicinal plant materials are suggested to be inspected and sorted prior to primary processing. The inspection includes virtual inspection for cross-contamination by untargeted plants/plant parts and for foreign organic matter as well as organoleptic evaluation of appearance, damage, size, colour, odour and taste.

Appropriate measures of primary processing are dependent on the specific features. These processes should be carried out in conformity with the national/regional quality standards, regulations and norms, however, purchasers may require specific protocols as well. The protocols should also comply with national/regional regulatory requirements applied in the producer’s and the purchaser’s countries.

Standard operating procedures should be followed. The harvested raw material should be promptly unloaded and unpacked upon arrival at the processing facility (to prevent fermentation and thermal degradation).

Medicinal plants applied in fresh form are to be stored under refrigeration or conserved by other methods approved by the producer and end-user countries. Inspection have to be made for substandard (discoloured, damaged, mouldy) products or foreign organic matter (soil, insects, and foreign plant parts) and they should be eliminated. Mechanical devices have to be cleaned and maintained as well as protected from insects, rodents birds and other pests.

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Fresh chamomile flowers waiting for drying in the processing plant of Herbária in Balmazújváros, Hungary (Photo: Pluhár, 2011)

Moisture content of the material harvested should be kept as low as possible to reduce damages from mould or other microbial infestation. Information on the appropriate moisture content for particular medicinal plants is available in the Pharmacopoeias and authoritive monographs. Medicinal plants are dried in a number of ways. When possible, temperature and humidity should be controlled to avoid damage of the active compounds. The drying conditions should be recorded.

Guidelines concerning building and drying facilities are also involved in GACP.

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Steam sterilizing equipment (a) and the drug under treatment (b) in the processing plant of Herbária in Balmazújváros, Hungary (Photo: Pluhár, 2011)

 

Bulk packaging and labelling

 Processed plant materials should be packaged as quickly as possible to prevent deterioration of the product and to protect against unnecessary exposure to potential pest attacks and other sources of contaminants.

Clean and dry boxes, sacks, or other containers in accordance with standard operating procedures and regulations of the producer and the end-user are applied.

Reusable packaging material such as jute sacks and mesh bags should be cleaned (disinfected) and thoroughly dried prior to reuse, in order to avoid contamination by previous contents.

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Filling of sacks by dried drug in the processing plant of Herbária in Balmazújváros, Hungary (Photo: Pluhár, 2011)

A label affixed to the packaging should clearly indicate the scientific name of the medicinal plant, the plant part, the place of origin (cultivation or collection), the date, and the names of the grower, and the processor as well as quantitative information. The label should also bear a number that clearly identifies the production batch.

The records on all the processes should be kept for a period of three years or as required by national and/or regional authorities.

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Labelling used in the processing plant of Herbária in Balmazújváros, Hungary (Photo: Pluhár, 2011)

 

Control questions

 

 

What is the starting point of quality assurance in the case of medicinal plants?
a. the primary processing
b. the harvest
c. the propagation material
 
Which is the final measure inspected by GACP in the case of cultivated medicinal plants?
a. the harvest
b. the primary processing
c. the secondary processing
 
What does the quality certification mean?
a. a record on the result of quality control
b. an oral report of the grower on the measures done
c. showing the result of soil analysis
 
When should the quality be certified?
a. only during cultivation
b. only in the case of the drug produced
c. continuously during production
 
What should be controlled according to the specifications of the Pharmacopoeia?
a. a medicinal plant drug
b. a tea mixture
c. a herbal medicine
 
What is included in the ISO 9002 system?
a. quality control and management of production
b. guidelines for good agricultural practice
c. guidelines of WHO

 

Right answers

 

Reference list

 

 

  1. Anonymus (2004): Pharmacopoeia Hungarica. VIII. kiadás. Budapest, Medicina Könyvkiadó.

  2. EUROPAM (the European Herb Growers Association GAP/GWP Subcommittee) (2006): Z. Arzn. Gew.Pfl. 2006. Vol. 11, 4:170-178.

  3. http://escop.com/

  4. http://www.ogyi.hu/kiadvanyaink/

  5. http://www.ogyi.hu/dynamic/Thymi_herba.pdf

  6. http://www.globalgap.org

  7. WHO Guidelines on Good Agricultural and Collection Practices (GACP) for Medicinal Plants. World Health Organization; Geneva, Switzerland: 2003. (http://whqlibdoc.who.int/publications/2003/9241546271.pdf)

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