Drug delivery formulation requirements

Writing down such mathematical expressions provides us with the experimentation volume required to completely characterize a test pool of components in multicomponent formulations. It also provides a systematic approach for design of experiments and data interpretation. Using the above mathematical expressions, we can estimate the number of experiments required to characterize a test pool of candidate enhancers for transdermal drug delivery formulations as a function of the size of the test pool. 

Compared to conventional tablet and capsule dosage forms, solid dispersion formulations are relatively complex drug delivery systems, requiring a substantially greater commitment of time, effort, and resources fordevelopment. Therefore, whetherthere is a need forsolid dispersion and whetherthi... 

Under certain circumstances, manufacturers may submit a new drug application (NDA) for an OTC drug product, which grants market exclusivity for a certain number of years. An NDA may be submitted for a current prescription drag to be marketed in a new formulation or dosage. A manufacturer of a product for which an OTC monograph exists is required to submit an NDA for a new drug delivery formulation, such as a sustained release product. 

Even if a medication is available in multiple formulations and dosage forms, the prescriber must consider the absorption and distribution differences between adult and pediatric patients. Blood supply at injection or infusion site, available blood supply for unit muscle mass, and skeletal muscle mass relative to body mass vary with patient age and size, causing drug absorption to vary, as well. A rapid intravenous bolus in a pediatric patient might result in acute toxicity a slow intravenous infusion, often required in neonates, can cause erratic, unreliable drug delivery in an older child. In addition, the volume of fluid tolerated for intravenous delivery varies significantly with the age and size of the patient. The blood supply and blood flow to and from the injection site are of prime importance since a gradual decrease in blood supply per unit muscle mass is seen with maturation. In addition, the skeletal muscle mass relative to... 

Intimately related to these factors is the design of the device, formulation, and the interface with the patient. Much of the discussion below will focus on the implications of excipients on formulation challenges for inhaled aerosol products. This chapter summarizes excipients for pulmonary formulations from several perspectives (i) excipient selection based on principles of delivery, (ii) physicochemical requirements for excipients, and (iii) specific challenges for formulations faced with aerosol drug delivery systems, including (a) biological aspects, (b) microbiological aspects, (c) analytical issues, and (d) future prospects. 

---