Industrial Pharmacy -II

Chapter 1

Pilot Plant Scale up Techniques

➣General Considerations

➣Significance of Personnel Requirements,

➣Space Requirements,

➣Raw Materials,

➣Pilot Plant Scale up Considerations for Solids, Liquid Orals, Semi Solids

➣Relevant Documentation,

➣SUPAC Guidelines,

➣Introduction to Platform Technology

General Considerations

Once a new drug molecule is discovered and it passes the pharmacological and toxicological tests, it goes to the formulation development department to create a suitable dosage form. The dosage form must be stable, able to release the drug at the right place and at the right time; so that the drug can exert its therapeutic effect. The dosage form should preserve the drug unchanged during its shelf life. To select and develop an appropriate dosage form, complete information about its absorption, distribution, metabolism and elimination of the drug is to be clearly understood by the formulators.

•Absorption a drug depends on its solubility, partition coefficient, and permeability. Knowledge of the site of absorption is also important in choosing the dosage form.

•Distribution of the drug within the body compartment depends on its solubility and lipophilicity. The biological half-life of a drug depends on its protein binding property. If the drug is highly bound, its half-life will be high because the bound drug cannot permeate to body tissues and thus, its metabolism and elimination will be delayed.

•Metabolism is the conversion of a drug from its lipid-soluble form to a mostly water-soluble form; so that it can be eliminated from the body. The liver is the main organ in which most of the drugs are metabolized. There are some enzymes, which can metabolize a drug by chemical means - oxidation, reduction, and hydrolysis. Cytochrome P450 plays an important role in the enzymatic metabolism of a drug.

•Excretion is the elimination of a drug either in metabolized form or as such from the body through urine, faces, sweat, etc. The kidney plays an important role in the excretion of a drug.

A formulation should be developed in such a way that it can be manufactured economically on a large scale repeatedly without any change in its characteristic property. The formulation is initially manufactured in laboratory scale using laboratory-sized commercial equipment’s and machinery. This is done to avoid the variation in quality between the large scale/commercial production due to the changes in equipment’s. The lot size of the laboratory scale is also less than that of the pilot scale production. This is done to reduce the expenditure and to increase the number of lots. In both cases, the cGMP must be followed.

Once the formulation manufactured in the laboratory is found to be of consistent quality as per expectation, the formula is tried in pilot scale. In pilot scale, the lot size is increased and the method of manufacture, specifications of the raw materials used and those of the products are noted. The Fig. 1.1 expresses how the technology is transferred. All the processes are carried out as per the documented method and keenly observed. Any deviation in the method or characteristic properties of the intermediate or of the final product must be recorded. During the pilot plant scale production following points are to be documented.

•The availability and quality of each raw material

•Time required to complete each and all the processes

•Quality of intermediate at each step

•Processing parameters

•Environmental conditions for each process required

•Equipment’s and machineries required and their specifications

•Space required

•Types of personnel required

•Processing loss

•Yield

•Methods of evaluation of intermediates and final product

•Specifications of the raw materials and finished products

•Type and quality of packaging material required

•Storage conditions for intermediates and final product

•Shelf life of the products

Once the product produced complies strictly and consistently with the specifications, it may be considered that the pilot scale production is completed and the technology is ready to scale-up before transfer to commercial production. After successful completion of scale-up trials, the technology is transferred with all relevant documents to the production department for large-scale production. Thus, a pilot plant is a small industrial system, which is very similar to the large-scale production and is operated to generate information about the behavior of the system for use in the design of larger facilities. A pilot plant is an intermediate step in between the laboratory scale and industrial/large scale. These are usually smaller than full-scale production plants, but are built in a range of prototype sizes. (A pilot plant is a small-scale replica of the full-scale to provide design data for the ultimate large-scale production).

Usually, in the formulation development or research & development section, if the lot size is 1000 units, in the pilot scale, it becomes 10 000 and in the scale up, the lot size is increased to about 1 00 000, while in commercial production, the lot size becomes 5 - 10 lakhs. In other words, from R & D to the commercial scale, the lot size is increased as

1. →10X → 100X → (500 – 1000) X.

Objective of scale-up technique

•To develop a physically and chemically stable, therapeutically effective formulation, by optimizing various parameters.

•To create guidelines for production and process control.

•To develop specifications for raw materials handling and its requirements.

•To identify the critical steps and parameters involved in each process.

•To develop a master formula for manufacturing the dosage form.

•A pilot plant study was conducted to develop a formula identical to a commercial batch.

•Selection of infrastructural requirements to scale up the pilot plant.

•To evaluate, validate and finalize the production and processes.

•To evaluate and validate the developed product.

•To enlist the processing equipment.

•To establish the physical and mechanical compatibility of the equipment with the formulation.

•To determine the time and cost factor.

•To meet the needs of current market strategies.

•To transfer the technology from small scale to large scale production shown in  Fig. 1.2.

Steps involved in scaling-up of a technology

During transfer of a technology from pilot scale and to large-scale manufacturing through scaling-up of technology following processes are followed as shown in Fig. 1.3.

Significance of Personnel Requirements

Most of the departments require people of different categories in terms of their level of education and work experience. Accordingly, they are assigned to different administrative levels. The activities in a pilot plant mostly require skill workmanship because a particular work needs to be completed within a minimum period. Persons lower than supervisor level working in a pharmaceutical pilot plant must understand why and how they are responsible and what may be the consequence of their failure. As such number of employees in a pilot plant department is limited, and depends on the number of products being developed. Usually 2-3 persons including product development scientist per product or two products are provided - an experienced scientist plus a knowledgeable and experienced operator, supported by an attendant. Therefore, the persons must have certain qualities, as listed below:

•Ability to read and understand the written directives/documents

•Intelligent analysis

•Ability to write the observations, requirements, etc.

•Possession of ethical values

•Possessing some hands-on experience of working in a pilot plant of a pharmaceutical industry

•Ability to communicate

•Ability to handle various equipment’s and machineries

•Some sense of engineering.

Space Requirements

In fact, there should be four sections of a pilot plant depending on the type of work to be carried out. Hence, there should four types of space requirements -

1. Administrative and information section

2. Physical testing section

3. Pilot plant Equipment section

4. Storage section

1. Administrative and information section

Documentation is a primary and essential activity in good manufacturing practices. Similarly, when some activities are going on information must be collected from various sources and needs to be communicated to some departments or some authorities. Thus, sufficient space should be provided to scientists and technicians working in a pilot plant to perform these activities. This space or section is called an administrative and information section. The location of this area should be adjacent to the work area but should be isolated from the work area so that the people can work without any disturbance.

The function of a pilot plant is to convert and transform the outcome of research and development activities into a feasible input of commercial production. People from the R&D department as well as those from the production department are expected to come to the pilot plant to discuss different issues. Thus, an adequate space is required so that at least five to six people can seat comfortably and discuss without disturbing other activities. At the time there should be an information centre attached to this section; where in a computer and printer must be available with internet facility to ensure that the information can be collected and documentation can be made conveniently.

2. Physical testing section

The next area or space must conduct experiments such as physical tests on the products prepared. This is a working area. There should be bench-top to keep the instruments required to perform mostly the physical tests and the samples. Commonly, the balance, pH meter, moisture balance, viscometer, desiccators, etc. Are to be placed on the bench-top. The space provided should be adequate to perform the tests comfortably.

3. Pilot plant equipment section

This is a standard pilot plant equipment floor area where the equipment required to manufacture different types of dosage forms is placed. Usually the equipment used in a pilot plant is similar to that used in an actual production department. These should be of different sizes. With the quality of scale up data collected can be assured, particularly when expensive materials are used. To evaluate the effect of the scale of research formulation and process, intermediate-sized and full-scale production equipment’s would be required. In other words, to obtain the equivalence between the qualities of the products produced in a pilot plant and those produced in large scale, similar equipment’s must be used in pilot scale production. This area should be used most efficiently; hence, it should be subdivided into different areas required as per the type of dosage form such as solid, semi solid, liquid, and aerosol manufactured.

Since, the dosage forms are irregularly manufactured in pilot plants as per requirement, use of pilot plant equipment’s is also irregular; hence, the equipment in the pilot plant should be portable. The equipment is used only when a product is developed in the R&D department and needs to be scaled up. Thus, all the equipment is not used daily in the pilot plant department. These should be stored in a small area and be taken out before use. With this system, congestion can be removed, working space is increased and people can work comfortably. If sufficient space is there around each of the equipment’s, the equipment can be cleaned easily and properly. There are equipment’s which are used after cleaning in place and some are used when placed in clean area.

4. Storage section

This is the fourth area. Usually this space is found to be insufficient for storing of equipment’s. Apart from equipment’s, excipients, including actives (drug substances), packaging materials and finished products are to be stored orderly. All these materials should not be stored in a single area. Each category should be kept separately. Hence, the storage area should be subdivided into at least three areas - one for storing the equipment’s, in the second area excipients, and in the third area-finished products should be stored. The second and third areas need to be subdivided further to reject, under test, and approved materials as per GMP. According to GMP, the packaging materials are to be stored separately, not with raw materials. The raw materials and finished products should be stored at different conditions of temperature and humidity. For example, some materials require low temperatures and humidity. Some require a dry place.

The packaging materials are usually bulky in nature and require more space. Finished products are stored as retained samples to use as a reference till it is expired. The retained samples (finished products) should be stored as per the specifications provided in the label. These samples were tested to assess their stability under different environmental conditions. Therefore, the storage area should be provided according to the requirement with different environmental conditions. For example, capsule shells require low humidity and temperature. Bottles, vials and ampoules are stored under normal atmospheric conditions. Boxes of different categories are stored under normal atmospheric conditions.

Raw Materials

The responsibility of the pilot plant scale up department is to approve and validate the raw materials required for the product. Raw materials also include an active ingredient. Because the physical characteristics of raw materials used in small pilot batches may differ when these are used in large amounts. The analytical specifications of the materials including drug substance do not change, but their physical specifications such morphology, particle size, particle shape, colour, bulk density, static charge, flow properties, the rate of solubilization, etc. It is also necessary to verify the quality of the final product by using excipients including drug substance manufactured by other companies or supplied by different vendors; because to maintain an uninterrupted production schedule there should always be some alternative suppliers or manufacturers who can fulfill the requirement of materials in terms of quality and quantity.

Processing Equipments

The attributes of final products in most cases depend on the type of equipment used in processing. The equipment should be simple in operation, economical and should be easily cleaned and maintained. In the formulation development section, equipments of small capacity are generally used. Sometimes, the equipments used in formulation development work does not match with what is actually used in large-scale production. Hence, the feasibility of the manufacturing processes is developed in formulation development and processing characteristics are determined. Once the process parameters and feasibility are established, pilot plant trials are conducted using large - scale production equipments with small capacities. If the desired equipment’s is not available in house, the trial experiments of the pilot plant can be conducted at the equipment vendor’s house to examine the feasibility and effect of equipment on the final quality of the product. Sometimes the quality of the intermediate product and time required to complete the process depends on the type of equipment used. For example, there are different types of mixers used in wet granulation, each has a different mixing efficiency. Hence, which mixer would be suitable for a particular product that needs to be decided? Similarly, for drying wet granules or even powders fluid bed dryer or hotair oven (tray dryer) can be used. But it may be necessary to decide the suitability of the dryer. If the capacity of the equipment is very small, it may be difficult to scale up the technology to a commercial scale. However, if the capacity of the equipment is large, the size of the experimental lots would be high and the cost of the equipment’s would be high. Thus, overall expenses would be high. In fact, it would be very much difficult to run a trial experiment on an expensive drug.

When the process or technology developed is found to be realistic intermediate-sized batches are run before large-scale production.

Production Rate

In any industry, it is necessary to know how much and how long a product can be sold in the market. Depending on market requirements, the production rate should be fixed. To meet higher requirements, the rate of production should be increased and for this, equipment’s of higher capacity would be required. This requires more capital investment. The following points should be considered before purchase of equipment;

•Cost of the equipment

•Whether the equipment can be used to manufacture other products or not?

•How frequently the equipment is used?

•Whether the operation and cleaning of the equipment are easy?

•Whether special training is required for the operation and maintenance of the equipment?

•What would be process-loss?

If the purchase of the equipment with a higher capacity is impossible, continuous operation of processes using equipment’s of lower capacity and finally the intermediates are mixed and made a single batch. Accordingly, the production rate can be increased.

Process Evaluation

The knowledge of the effects of various process parameters as few mentioned above forms the basis for process optimization and validation. Any manufacturing process is necessary to be evaluated on the basis of certain critical parameters, as shown in Fig. 1.5.

Pilot Plant Scale-up Considerations for Solids, Liquid Orals, Semi Solids

The primary responsibility of the pilot plant staff is to demonstrate that the product (dosage form) developed is therapeutically efficient, economical, and consistently reproducible on the production scale. The design and construction of the pharmaceutical pilot plant for every dosage form development should be such that the flow of materials, processes, and personnel are as per the norms of GMP and facilitates the maintenance and cleanliness of the area and equipment’s. Irrespective of the type of dosage form, the processes are performed systematically. Each stage/step must be monitored very carefully and thoroughly starting from collection and storage of excipients to the manufacturing processes and quality of product. At each step, the tests (IPQC tests) to be performed on the intermediates are enlisted to control and ensure the desired quality of the final product. It is to be established that the the same process, same equipment’s of higher capacity when used with increased amounts of material does not change the quality of the product.

Solid Dosage Form (Tablet)

When a particular dosage form is developed by the R&D department and after that is sent for pilot plant scale up studies, the formula developed is standardized. The processing equipment’s to be required for large-scale production are reviewed. The rate of is very much important for any manufacturing business; through a pilot plant study the rate of production is optimized and controlled. In fact, the infrastructural requirements for commercial manufacture are also known. While increasing the rate of production (scale up activity) the critical parameters are determined. Simultaneously, appropriate records to be maintained as per the GMP are known.

Steps involved in Tablet Production

The actual steps involved in the manufacture of tablets depend on the method used such as direct compression, dry granulation, and wet granulation. Irrespective of the method used, there are some common steps such as;

•Material handling

•Granulation

•Drying

•Reduction in particle size

•Blending

•Compression

In case of direct compression, the powders are mixed, lubricated and compressed. In case of dry granulation method, the blended powders are compressed to make slugs. The slugs are then crushed to make granules; the granules formed are blended with lubricant and diluent, if necessary and then compressed. When the tablets are prepared by wet granulation method, the powders are mixed first, then granulated with paste or solution of suitable binder, passed the wet mass through appropriate sieve, the wet granules are dried, crushed to form appropriate sized granules, the granules are then blended with lubricant; if necessary, and then compressed.

Material Handling System

In laboratory operations, the materials are handled simply by hand such as scooping, drawing or pouring. In intermediate- or large-scale operations, the materials are often handled by a suitable mechanical system such as vacuum loading systems, metering pumps, screw feed system. Note that when materials are transferred for the manufacture of more than one product, there is no cross contamination. The material handling system must deliver the accurate amount of the ingredient to the formulation. The Selection of the type of mechanical handling system depends on the materials such as density and static change.

Weighing of materials is an important activity in manufacturing either in small scale or large scale. The accuracy of the strength and quality of the product manufactured depends on the addition of all materials that are accurately weighed and processed properly. Weighing in a common processing area may cause problems such as

➣Cross contamination, and

➣Products may become misbranded due to the presence of incorrect amount of drug or due to the presence of minute amount of drug other than the declared one.

For this reason, some industries have weighing sections that are separated from other sections. This section means only weighing activity. After each weighing, it would be checked by another person and countersigned. According to product and its lot size, the amount of drug required is calculated and then weighed. This ensures that the correct quantity of drug is used in the manufacture of each lot. Each weighing balance is regularly maintained and calibrated by an authorized agency. This is a central department responsible for correct weighing. The sanitation, particulate matter in the circulating air are controlled in the area up to the highest degree.

A separate room or area is provided to weigh a highly potent drug such as steroid or alkaloid. The area is equipped with an efficient air filter, so that even minute contaminations do not occur. However, such an area can be used to weigh the dyes.

Dry Blending

The blending of powders should be done properly, otherwise uniform mixing would not be there. That is, samples of different portions of the mixture would show different potency. To ensure uniform mixing all the ingredients should be free from lumps and agglomerates. Hence, screening and/or milling of the ingredients are done before mixing to make the mixture homogeneous and reproducible. The equipment used for blending are V- blender, double cone blender, Ribbon blender, slant cone blender Bin blender, orbiting screw blenders, Vertical and Horizontal high intensity mixers. The process of blending or mixing can be optimized by controlling the following parameters:

•Time of blending

•Blender loading

•Size of blender

It is well-known fact that the mixing of powders to make a homogeneous mixture is a challenging work. There are certain ways to achieve homogeneity. The order of addition of components should be monitored. The smallest amount is mixed with the small one; the mixture is then mixed gradually with portions of the powder of large quantity; like this. By this method, the drug can be uniformly distributed within the powder mix and variation in drug content can be reduced greatly, particularly when a small amount of drug is present in a unit dose such as per tablet or capsule. Mixing or blending of powders