Pharmaceutical Dosage form Design and Manufacture

Pharmaceutical dosage form design and manufacture go through numerous steps. Some of them discuss on this article briefly.  We hope this article will be more helpful for a industrial pharmacist.

Formulation development is a most important part of pharmaceutical dosage form design and manufacture. Formulation is the process o developing a drug candidate into a drug product. Initially, there may be a number o potential drug candidate molecules, each with a unique set o physicochemical properties and each showing activity towards a particular biological target. 

Ultimately, only one (at best) will be developed into a drug product. The decision to select a successful drug candidate to be developed does not depend on pharmacological efficacy alone. In practice, the physicochemical properties o the molecule affect how a material will process pharmaceutically, its stability, its interaction with excipients, how it will transfer to solution and, ultimately, will determine its bioavailability.

Physicochemical properties can be split into those that are intrinsic to the molecule and those that are derived rom bulk behavior (e.g. of the powder or crystals). Intrinsic properties are inherent to the molecule and so can only be altered by chemical modification, while derived properties are the result of intermolecular interactions and so can be affected by solid-state form, physical shape and environment among other actors.

Determination of these properties or a new chemical entity is termed preformulation (literally the stage that must be undertaken before formulation-proper can begin). Preformulation aims to optimize the process of turning a drug candidate into a drug product. During preformulation, the physicochemical properties of drug candidates are determined. Its include - 

• Solubility
• Melting point
• Partition coefficients
• Particle size distribution
• Polymorphism etc.

The oral route is the most common way of administering drugs and among the oral dosage forms, tablets of various kinds are the most common type of solid dosage form in contemporary use. 

A tablet consists of one or more drugs (active pharmaceutical ingredients) as well as a series of other substances (excipients) used in the formulation of a complete preparation.

Stages in tablet formation:

• Material dispensing
• Granulation/ Processing
• Mixing & lubrifaction
• Compression - Die filling, tablet formation, tablet ejection.

Tablets are formed in a variety of shapes. The most common tablet shapes are round, oval and oblong but tablets may also have other shapes, such as triangular or quadratic.

Coatings may be applied to a wide range o oral solid dosage forms, including tablets, capsules, multiparticulates and drug crystals. While tablets represent the class o dosage form that is most commonly coated, coated multiparticulates are also popular. Three main types of process are used in the pharmaceutical industry today:

1. film coating
2. sugar coating
3. compression coating

Another convenient dosage form is Capsule. There are two types of capsule, ‘hard’ and ‘soft. The hard capsule consists of two pieces in the form of cylinders closed at one end; the shorter piece, called the ‘cap’, its over the open end of the longer piece, called the ‘body’. 

Softgels consist of a liquid or a semi-solid matrix inside a one-piece outer gelatin shell. Ingredients that are solid at room temperature can also be encapsulated into softgels providing they are at least semi-solid below approximately 40 °C. The drug compound itself may be either in solution or in suspension in the capsule- fill matrix. The characteristics of the fill matrix may be hydrophilic (for example, polyethylene glycols), lipophilic (such as triglyceride vegetable oils), or a combination of hydrophilic and lipophilic ingredients.

Related:

• Types of Pharmaceutical Tablets
• Bi-layer Tablet Technology in Pharmaceutical Industry
• Selection of Dissolution Medium for Oral Solid Dosage Form
  
• Generic Drug Development Process