Medicine Manufacturing: Steps Involved and Types

Introduction:

There are various types of medicines ranging from veterinary to medicines for human usage. Over the course of time, conscientious and diligent research has been put into improving the quality and effectiveness of medicines. There are hundreds of thousands of medicines available today meant for different ailments but this galore of medicines can be divided into three basic categories

• Tablets
• Syrups
• Gel

Every medicine available comprises of two main constituents: Active ingredient and Additives/Excipients. The main remedy is the active ingredient. Whereas, the additives are added to inculcate rigidity, to increase the quantity so that the raw materials can be easily processed and to dissolve certain active ingredients.

All human medicines that are produced on industrial scale must go through extensive testing and if its deemed fit for human usage it is produced commercially. There are various standards that are set to test the quality of medicines such as: European directorate for the quality of medicine (EDQM) and U.S pharmacopeial convention (USP).

Tablet Manufacturing:

In order to make the process more intuitive a specific product (Aspirin) will be discussed.

1. Raw materials:

• Phenol
• Sodium hydroxide
• Carbon dioxide
• Acetic anhydride
• Hydrogen
• Corn starch
• Water

2. Weighing:

The corn starch, the active ingredient, and the lubricant are weighed separately in sterile canisters to determine if the ingredients meet pre-determined specifications for the batch size and dosage amount.

3. Mixing:

The corn starch is dispensed into cold purified water, then heated and stirred until a translucent paste forms. The corn starch, the active ingredient, and part of the lubricant are next poured into one sterile canister, and the canister is wheeled to a mixing machine called a Glen Mixer. Mixing blends the ingredients as well as expels air from the mixture. The mixture is then mechanically separated into units, which are generally from 7/8 to 1 inches (2.22 to 2.54 centimeters) in size. These units are called slugs.

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4. Dry Screening:

Next, small batches of slugs are forced through a mesh screen by a hand-held stainless steel spatula. Large batches in sizable manufacturing outlets are filtered through a machine called a Fitzpatrick mill. The remaining lubricant is added to the mixture, which is blended gently in a rotary granulator and sifter. The lubricant keeps the mixture from sticking to the tablet machine during the compression process.

5. Compression:

The mixture is compressed into tablets by a punch machine. On single-punch machines, the mixture is fed into one tablet mold known as dye cavity by a feed shoe, as follows:

• The feed shoe passes over the dye cavity and releases the mixture. The feed shoe then retracts and scrapes all excess mixture away from the dye cavity.
• A punch of the size of the dye cavity descends into the dye, compressing the mixture into a tablet. The punch then retracts, while a punch below the dye cavity rises into the cavity and ejects the tablet.
• The feed shoe returns to fill the dye cavity again, it pushes the compressed tablet from the dye platform.

6. Coating:

Tablets may be coated to reduce swallow difficulties or target specific part of the body where the coating will dissolve and take effect. Coating is done by adding desired coating solution to the drum along with the tablets. Blowers are used to rapidly dry the coated tablets and prevent sticking.

7. Testing:

The compressed tablets are subjected to a tablet hardness and friability test, as well as a tablet disintegration test.

8. Packaging:

The tablets are transferred to an automated bottling assembly line where they are dispensed into clear or color-coated polyethylene or polypropylene plastic bottles or glass bottles. The bottles are topped with cotton packing, sealed with a sheer aluminum top, and then sealed with a plastic and rubber child-proof lid. A sheer, round plastic band is then affixed to the circular edge of the lid. It serves as an additional seal to discourage and detect product tampering.

Syrup Manufacturing:

1. General manufacturing procedure:

Syrups should be carefully prepared in clean equipment to prevent contamination. Three methods may be used to prepare syrups.

• Solution with heat
• Agitation without heat
• Percolation

Although the hot method is quickest, it is not applicable to syrups of volatile ingredients. When using heat, temperature must be carefully controlled to avoid decomposing and darkening the syrup.

Syrups may be prepared from sugars other than sucrose (glucose, fructose), non-sugar polyols (sorbitol, glycerin, propylene glycol), or other non-nutritive artificial sweeteners (aspartame, saccharin) when a reduction in calories properties is desired, as with the diabetic patient. The non-nutritive sweeteners do not impart the characteristic viscosity of syrups and require the addition of viscosity adjusters, such as methylcellulose. The polyols, though less sweet than sucrose, have the advantage of providing favorable viscosity, reducing cap-locking (which occurs when sucrose crystallizes), and in some cases acting as co-solvents and preservatives.

2. Cough syrup manufacturing process:

Traditional cough mixtures are formulated around a syrup at 60-75% concentration which is made from sucrose, malt dextrin, glucose, invert syrup etc. The remainder is made up of thickening agents, stabilizers and active ingredients. Manufacturers of cough mixtures generally produce their own syrups as this offers greater control of product quality. The manufacturing process must achieve several functions:

• Dissolving of the sugars to form a syrup
• Hydration of powdered ingredients
• Blending ingredients of widely different viscosity
• Suspension or dissolving of active ingredients
• The end product must be smooth, agglomerate-free and homogeneous.
• High Shear mixer is used for mixing.

Gel manufacturing Process:

1. Raw materials:

Aluminium Acetate, Povidone Iodine, Propylene glycolCremophor RH 40, Lutrol F 127, Cetylstearyl alcohol, Cremophor A 6, Liquid paraffin, Parabene(s), Alpha-Bisabolol, Triethanolamine, Kollidon 30, Benzoyl peroxide, Betamethasone valerate etc.

2. Heating:

The temperature should be high enough to ensure the intimate mixing of liquid phase and to prevent the premature crystallization and congealing of its components. Ointments preparation involves separate oil and water phases containing the required ingredients, heating each phase to between 60-70°C.

3. Mixing:

Mechanical mixers, such as a steel jacketed kettle with agitator are commonly used to prepare semisolid preparations in pharmaceutical industry. The use of mechanical shear or a combination of fusion processes and mixing can be used to facilitate the dispersion or dissolution of the ingredients in the base to form a single-phase ointment. Time, temperature, and mechanical energy input are the three major variables in the manufacturing of semisolid preparations.

4. Emulsification:

After the mixing process, the mixer is send to the emulsifier where the immiscible layers are forced to form an emulsion.

5. Cooling:

Cooling rate can influence the final product quality. Different cooling rates after melting, mixing, and emulsification steps should be investigated as a process variable. The most important aspect of manufacture is to ensure all ingredients are fully dissolved and well mixed before packing and that the formulations contain suitable effective preservatives. Mixing is continued with cooling until the cream/gel is formed.

6. Packaging:

After cooling, the gel is packed. In suspension, mixing of the bulk must be continued during packing to ensure even dispersion of the active ingredients at all times.