Granule manufacture

Introduction:

Tablets are the single most common formulation used today. They account for 50% of total market share. The main reasons for this are the many advantages that come with formulating a drug as a tablet, such as:  Relative ease of manufacture compared to a cream for example  Uniformity of dose, compared to a suspension  Stability of dosage form, tablets can have a shelf life of over a year  Controllability of drug release. This does not occur in formulations such as creams.

The ingredients of a tablet differ from one drug to another, and the different compositions will be reflected in the tablets therapeutic effectiveness.

Variations in particle size will be reflected in a tablets physiochemical properties. A tablet will contain, primarily, the active ingredient, i. e. the drug that is being delivered. The tablet will also contain other ingredients that are necessary to formulate a satisfactory tablet, these ingredients are called excipients, and common excipients include: Binders: such as polyvinylpyrrolidin (PVP).

These exert an effect by holding particles together; they induce the formation of granules. Diluents: such as lactose and microcrystalline cellulose.

Diluents are used to increase the mass of the powder, for example if the over all mass of a tablet needed to be increased to 50mg, a diluent would be ideal to o this. Glidants: such as colloidal silica. These act by reducing interparticulate friction. This allows the powder particles to flow better, which is an advantage during the mixing process. Lubricants: such as magnesium stearate. This is a useful excipient which has two major effects.

It helps to reduce the friction between granules and the tablet machinery and also improve the flow properties of the granules.

Disintegrants:

such as maize starch. These are essential as they improve the capability of the tablets to break apart in water. Once the tablet enters the body, it begins to disintegrate, the better the disintegrant, the faster dissolution will occur. The table disintegrates into smaller particles with a large surface area. This increased surface area increases the rate of dissolution. When deciding on what excipients a product will include we look at the following properties, the dose of the drug, particle size, particle shape, solubility, stickiness and powder flow of drug material.

The diluent that will be used is also chosen on the basis of these properties. We try to mix in diluents of similar shape and size to the drug particles and try to mix in a soluble diluent. Lactose increases the hydrophilicity of the formulation allowing water to come in and penetrate the formulation. One method of aiding flow properties and improving the efficacy of the overall tabletting process is by the formation of granules. The granulation process involves combining smaller particles to from larger agglomerates. Granulation has many advantages such as increasing particle size which helps to improve flow properties.

Also the dispersion and solubility properties of a powder will be improved. There are two methods for granulation, wet and dry granulation. In this practical wet granulation was used. Wet granulation was advantages over dry granulation, it is better at improving cohesiveness and compressibility. Aim: To investigate the effect of varing the type of disintegrant (actisol and explotab) will have on tablet properties. To investigate the different particle sizes present in a powder Method:  The various tablet ingredients were weighed out individually in tared containers (according to the amounts featured in table 1).