intro

developing an appropriate dosage form accounting for physicochemical drug properties, stability, route of delivery, etc.

novel means of improving efficacy of medicine or patient compliance, reducing side-effects, targeting drug to specific cells/tissue, etc.

Biopharmaceutics is the study of those factors which modify the performance of pharmaceutical dosage forms and how this information can be used to optimize these so-called «drug delivery systems». understanding the absorption, distribution, metabolism and excretion of drugs following administration and applying this to the design of dosage forms.

ensuring that standards of purity, identity, dosage and safety are met throughout the process of manufacturing a medicine.

according to the FDA, “…the science of developing new tools, standards, and approaches to assess the safety, efficacy, quality, and performance” of medicines.

MW Lipophilicity Ionization Solubility vs pH Dissolution rate Chemical stability Particle size, crystallinity and hygroscopicity for solid drugs Compatibility with excipients and packaging materials

“Getting the right drug to the right place at the right dose and at the right rate”. “The right medicine/treatment for the right patient” Rate and extent of drug absorption and the definitions of biopharmaceutics, pharmacokinetics and pharmacodynamics. Identification of the principal barriers to oral drug absorption

Weakly acidic and basic drug molecules – the Henderson-Hasselbalch equation. Drug solubility as a function of pH. Optimising drug properties to ensure good oral bioavailability. What is log P, how is it measured and why is it a useful parameter? Lipinski’s Rule-of-5: criteria for drug molecular weight, lipophilicity and hydrogen bonding ability. Exceptions and strategies for “difficult-to-deliver” drugs

Potent drugs are only useful if they reach their site(s) of action Drug delivery technology can optimize therapy (increase efficiency, minimize toxicity) Drug design and development to include analysis of delivery options

What the drug does to the body

What the body does to the drug

is a quantitative measure of the amount of a drug that reaches its site of action and of the rate at which it gets there it allows comparison of different drug delivery systems

Dose metabolite drug in urine drug concertation in plasma LADME

Transfer of drug from its formulation at site of administration to systemic circulation Practically speaking, several routes of ‘delivery’ are possible: Oral intramuscular injection subcutaneous, intradermal injection implant topical and transdermal inhalation ocular, nasal, buccal rectal, vaginal

Equally, high dose (low potency) drugs can be a problem to formulate If drug has poor flow/compressability cannot make a tablet capsule