Formulation development in pharmaceutics is the stage in which the drug that was manufactured for a specific purpose is prepared to be taken by patients. It entails the combination of different chemical substances, the active drug included, into the end product, which may be in form of a tablet, capsule or syrup.
Before the formulation stage is reached, there a pre-formulation step, whereby the chemical, mechanical and physical characteristics are studied. This step is important in choosing other substances, aside from the active drug; which are also known as excipients, which will be used in the formulation development.
A special case of pre-formulation is subjected to drugs which have protein properties within them. Since the protein solutions are usually affected by such stress conditions as temperature and the pH levels, due care is taken to factor in those conditions. Effects of freezing and thawing are of particular importance in their pre-formulation stage. Other mechanisms of degradation which dictate their expiry dates are also studied at this juncture.
The key to formulation development is the output, which is a stable drug. This is a drug that can be accepted by the body of the patient. For example, drugs which are to be taken orally are made palatable, at this stage. The output, which may be a capsule or a tablet, will have to be taken through a series of tests to ascertain its safety.
The tests are designed to offer insight into the interaction between the different substances which make up the tablet or capsule. Factors which affect bio – availability are considered here; including the sizes of particles making up the tablets, polymorphism and solubility of these particles.
Incorporation of Inactive Additives
While still in the formulation development stage, inactive additives are added to the emulsion from which the tablets, capsules or syrups will be derived. This is done in a controlled manner, which seeks to give even distribution of the different constituents within the emulsion. This ensures that consistency of the contents will be guaranteed for every dosage unit.
Inactive additives also have a secondary function to the end result. They make the drug have uniform appearance, not to mention the safeguard against tablet or capsule disintegration. Moreover, the additives are put in place to provide acceptable taste and hardness of the tablet.
Lipids have recently been widely recognized as some of the best ways in which the delivery of the drugs to the body is assured. Lipid formulation, as a result, has been designed to address the problems faced by the mainstream formulation development methods, which is limited drug bio- availability and solubility.
A second advantage with lipids is that they are a safe way of drug administration. The delivery of the dosage within the bloodstream is facilitated with the liposome drug carriers, which are added in the formulation development stage. Lipids are also compatible with other methods of pharmaceutical drug administration, such as ophthalmic, oral, topical or even parenteral means.
Bench Studies and Clinical Trials
Soon after the main part of formulation has been completed, an overlapping process which provides the basis for finishing touches is started. This entails the testing of pilot patches to evaluate the extent to which optimization is still needed to be undertaken. A small amount of the end product, called the diluents, is taken for testing.
The results are analyzed according to different drug loads. The typical results are that low drug loads may cause problems to do with homogeneity, in which typical physiological solutions will not have an even distribution of the active drug. On the other hand, high drug load might cause problems to do with flows; or call for the use of large capsules, if the intention of the formulation of the drug was to provide medication with a low bulk density.
Closing of Containers
The final process of formulation development is the placement of the pharmaceutical product in a sealed container, for an extended period of time. There are different types of containers for different drug preparations. Some of the containers are bottles, syringes, vials, blisters, ampoules, among others.
During this final stage, there is a careful study done on the interaction between the container and the drug. This could give insight as to what to use in the packaging of the final product, in order to avoid any contamination before the unpacking. An additional study is carried out to test the sensitivity of the drug to sunlight. If there is any effect of light on the contents of a transparent packaging, it is best to use translucent or opaque alternatives in the manufacturing line.