Knowledge management in pharmaceutical industry
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20th September 2001

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Raw material sampling and dispensing

Sampling needs to be done in accordance with approved written procedures in order to detect contamination by environmental microbes says R Kedareshwar

Unlike in other industries, in pharma quality has to be built into the product by following the well-laid down SOPs (standard operating procedure). End product testing only will indicate whether the product complies with the specifications. Quality of pharmaceutical products, if not manufactured in appropriate environment may pass the checks immediately after manufacturing, but may fail over a period of time (which is within the shelf life of the product). Also it is very much dependent on the ability and training of staff engaged in all processing, engineering, housekeeping and ancillary tasks associated with it.

Most of the samples need to be tested and analysed for microbial content against the specified limits. So, one has to ensure that during sampling environmental microbes do not contaminate the samples drawn. Hence now-a-days sampling is carried out in sampling booth or mobile tent equipped with LAF unit, where air is filtered through a Hepa Filter.

Sampling should be done in accordance with approved written procedures that describe:

  • The method of sampling
  • The equipment to be used
  • Instruction for any subdivision of the sample
  • The type and the condition of the sample container to be used
  • The identification of containers sampled
  • Any special precautions to be observed, especially with regard to sampling of sterile or noxious materials
  • The storage conditions
  • Instructions for the cleaning and storage of sampling equipment

Reference samples should be representative of the batch of materials or products from which they are taken, other samples may also be taken to monitor the stressed part of a process (e.g. beginning or end of the process).

Sample containers should bear a label indicating the contents with the batch number, the date of sampling and the containers from which samples have been drawn. On fixing this label it will be ideal to deface the suppliers approved label.


Raw materials required for formulations come in packs of various sizes like Aerosil 5kg bag, Hpmc 25kg, Titanium dioxide 25kg, Shellac 50kg etc., and actives like Paracetemol in 25kg bag. Accuracy of weighing is very critical, as any of the weighing errors will affect the composition of final product. Requirement of these ingredients varies from micrograms to kilograms based on the batch size.

Depending on the batch size each ingredient pack needs to be opened, necessary quantity transferred into a clean container (preferably SS316 or double polybag) and leftover material in the container to be closed and returned to approved storage area.

Here utmost care should be taken as most of the powders are white in colour and look alike, if by mistake labels of two ingredients fall down, identifying the correct material will be next to impossible and chances of committing major mistakes like mix-up are very very high.

Hence, the operation of dispensing should always be carried out in the presence of qualified chemists from production and quality assurance, for ensuring tracking and dispensing of required material in required quantities as per the BMR (batch manufacturing record). Always one needs to remember in dispensing is, a small mistake of wrong material or wrong quantity can take out the patient’s life.

All the raw materials and actives, excepients needs to be opened and transferred in the same quality of environment as manufacturing. Like class conditions, temperature and humidity. Further operating staff needs to be protected from exposure to any of the drug powders in general and potent drugs in particular (which may cause serious health hazards to the working personnel). So specially designed dispensing booths are employed.

Earlier only top point exhaust connected to central exhaust system used to be provided so that any powder rising while opening of container or transferring of the material would be exhausted out, but in the process when surrounding air is moving up it takes flying drug particles move over the operator’s breathing zone, thus exposing the operator to the active ingredients which will seriously affect the his or health. This is more serious in case of highly potent drugs like tranquilizers, antibiotics and biotechnology products etc.

Further the quality of the air is not controlled and is a point of concern for contamination, degradation in case of temperature/humidity sensitive products like aspirin, potassium clavulnate, dispersible formulations etc., So to overcome these problems dispensing booths are employed. Fig. No.1 shows typical dispensing booth of recent version. This is a down flow or reverse flow type with air being blown from top moving down and sucked from bottom level and passed through coarse filter followed by 5 microns of 95 percent and finally through HEPA (high efficiency particulate arrestor) filters to give class 1000 conditions (which is almost sterile air) and part of air is exhausted through additional HEPA filter on the front side as shown in the figure to ensure exhausted air free of drug particles.

These booths made of different materials:

  • Laminated MDF (medium density fiber board)
  • MS painted structure
  • Acrylic sheets with powder coated steel framework
  • Latest version is made out of stainless steel 304 sheet

HEPA filters ensure a laminar flow in dispensing zone, which is ideal for avoiding the spreading of drug particles. To ensure the laminar flow the filter conditions and blower speed play a critical role. As the filter gets blocked the airflow reduces affecting the air velocity. Now-a-days differential pressure gauges across each filter bank are provided to indicate the condition of the filters. If they are blocked/choked then first and second stage cleanable filters to be cleaned and fixed back. These differential gauges also monitor further filter integrity. Hence logging and checking of these differential pressure gauge readings is must before every dispensing. Operating personnel need to ensure that readings of these gauges are within specified limits before dispensing.

Advanced versions of dispensing booths are equipped with:

- Speed control mechanisms

- Differential pressure switches

- Microprocessor based controller, digital display unit

- Audible alarms in case of filters choking or any other malfunction

In stores and dispensing operations barcode/matrix code are employed to keep track of the movement of each and every container. Here the container is scanned at the first entry/inwarding point and moved by the AGV’s (automatic guided vehicles) to the allocated shelf by entering the shelf number in the computer, further once it is approved, it is moved on to the approved storage area by AGV.

From approved material storage area to dispensing again container labels are scanned for appropriate container as per the work order (given by the QA based on the production requisition which is in turn based on the production schedule). Once weighing/dispensing operations are over dispensed labels and complete record of the issued and dispensed materials is generated by the computer. Further, as the material is issued the stock records get updated accordingly. These dispensed labels are fixed on to the dispensed material bags thus avoiding any chance of mix-ups during the entire stores operation.

In this system, very few people can manage the entire stores operations. Again barcode scanners at the entry of dispensed material staging in production area ensure only the programmed and designated container enters into the particular manufacturing area. Here a word of caution to be noted. A computer controlled operations sound and look good but they need to be rigorousl checked for proven track record, the entire software should be thoroughly validated and should have provision for periodic validation. Otherwise, instead of aiding the manufacturing operations, it will become a major hindrance. Proven track record of software is essential and should be major criteria for selection of software.

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