Basic Of Solid Oral Dosage Forms - Tablet

SOLID ORAL DOSAGE FORMS

Historically, the most convenient and commonly employed route of drug delivery has been by oral ingestion.

Oral drug delivery has been known for decades as the most widely utilized route of administration among all the routes that have been explored for the systemic delivery of drugs via various pharmaceutical products of different dosage forms. 

It is considered as the most natural, uncomplicated, convenient and safe route.

Tablets are solid dosage forms containing medicinal substances with or without suitable diluents.

They are the most widely preferred form of medication both by pharmaceutical manufacturer as well as physicians and patients. They offer safe and convenient ways of active pharmaceutical ingredients (API) administration with excellent physicochemical stability in comparison to some other dosage forms, and also provide means of accurate dosing.

They can be mass produced with robust quality controls and offer different branding possibilities by means of colored film coating, different shapes, sizes or logos.

Capsules are solid dosage forms in which drug is enclosed within either a hard or soft soluble shell.

The shells are generally made up of gelatin. The capsules may be regarded as the container drug delivery system for powder and non powder filling such as tablets, capsules and pellets.

Advantages of Solid Oral Dosage Forms

• They are the most stable dosage form with respect to their physical, chemical and microbiological attributes. 

• Provide an accurate, stable dose with greatest precision and least content variability, easy to use, handle and to be carried by the patient. 

• They are attractive and elegant in appearance. 

• The manufacturing cost of tablets is low as compared to other dosage form and their manufacturing speed is also quite high. 

• The packaging and shipping of tablets is comparatively easy and cheap.

• The unpleasant taste and odor of medicament(s) can be easily masked

• The incompatibilities of medicament(s) and their deterioration due to environmental factors are less.  

• They are more suitable for large scale production.

• Their identification is probably the easiest because of variety of shapes and colors.

• They are formulated with certain special release profile products such as enteric or delayed release products.  

• They are the lightest and most compact dosage form.

Disadvantages of Solid Dosage Forms

• Drugs that are amorphous in nature or have low density character are difficult to be  compressed into tablet. 

• Hygroscopic drugs are not suitable candidate for compressed tablets.

• Drugs having poor wetting properties, slow dissolution profile and high optimal gastro intestinal absorption are difficult or impossible to formulate as a tablet.  

• Drugs having bitter taste and objectionable odor require special treatment like coating or encapsulation which may increase their production cost.  

• Some drugs which preferably get absorbed from the upper part of GIT may cause bioavailability problem in tablet dosage form.  

• Capsules cannot be used for extremely soluble materials such as potassium chloride, potassium bromide.  

• Capsules cannot be used for highly efflorescent or deliquescent fill materials.

Method of manufacturing of solid dosage forms  

Tablets 

Different types of tablet formulations are available, which could be broadly classified based on route of administration such as tablets for oral, sublingual delivery, buccal delivery,  rectal delivery or vaginal delivery and formulation characteristics such as immediate release tablets, effervescent tablets, melt-in-mouth or fast dissolving tablets, delayed release or extended release tablets. In all the cases, the general manufacturing process, machinery used for preparation of tablets and materials used are similar.  

TYPES OF TABLET MANUFACTURING.

The tablet manufacturing process can be broadly classified as

• Direct compression

• Granulation

Direct compression.

Direct compression is used when a group of ingredients can be blended, placed onto a tablet press and made into a perfect tablet without any of the ingredients having to be changed.  

Powders that can be blended and compressed are commonly referred to as directly compressible or as direct-blend formulations. The inherent physical properties of the individual filler materials are highly critical, and minor variations can alter flow and compression characteristics, so as to make them unsuitable for direct compression.   

The most widely used direct compression fillers are cellulose derivatives (e.g.  microcrystalline cellulose), saccharides (e.g. lactose and mannitol), mineral salts  

(e.g. Dicalcium phosphate, calcium carbonate) and partially pregelatinized starch.

Granulation

Granulation is an agglomeration process to improve the flow, density and compressibility

of particulate material by size enlargement and densification. Granulation can be achieved by

the use of binder solution (wet granulation) or dry binder (dry granulation).

Wet granulation 

When powders are very fine, fluffy, will not stay blended, or will not compress, then they  must be granulated. 

Wet massing is the process of adding a solution to a blended powder and mixing for a predetermined period of time at a given mechanical speed. 

Once the process is  complete, the wet mass is milled, spread on trays dried in a tray dryer. 

The formed granules are milled and compressed. Examples of wet granulation methods include fluid bed, high shear,

pelletization techniques, such as extrusion spheronization and spray drying.

Dry granulation

Dry granulation (roll compaction or slugging) involves the compaction of powders at high pressures into large, often poorly formed tablets or compacts.

These compacts are then  milled and screened to form a granulation of the desired particle size. The advantage of dry  granulation is the elimination of heat and moisture in the processing. 

Dry granulations can be produced by extruding powders between hydraulically-operated rollers to produce thin cakes that are subsequently screened or milled to give the desired granule size.

Granulation Methods

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