Biopharmaceutics Flashcards
What is biopharmaceutics?
The relationship between the physical and chemical properties of a drug in a dose form and the pharmacologic response after administration
What is biopharmaceutics dependent on?
- chemical nature
- physical state
- type of dosage form
- presence/ absence of excipients
- pharmaceutical process (type of granulation, tablet press, pressure applied to the tablet, friability, dissolution- all of these factors affect bioavailability)
What is the definition of pharmacokinetics?
Study and characterization of the time course of drug absorption, distribution, metabolism, and excretion.. The relationship of these process to the intensity and time course of the therapeutic and adverse effects of drugs. Also RELEASE of the drug (ie. from a solid dosage form)- part of absorption process
What is the definition of bioavailability?
Rate and extent (amount) to which a drug is absorbed from a drug product into the body or to the site of action
What is the definition of clinical pharmaceutics?
Is the application of pharmocokinetic methods in drug therapy. It involves a multidisciplinary approach to individually optimized dosing strategies based on the patient’s disease state and patient-specific considerations. (T1/2 varies from patient to patient - we assume that the patient is within 95% percentile of thousands pf patients but chances are they are not)
What is the definition of pharmacodynamics?
Refers to the relationship between drug concentration at the site of action (receptor) and pharmacologic response
What is the 4 factors that contributes to biopharmaceutics?
Absorption
Distribution
Metabolism
Excretion
What affects drug absorption?
- transport processes, pH, lipophilicity, particle size, first pass effect– drug dissolution rate also affects drug absorption
What affects drug distribution?
- body fluid compartments, tissue distribution, protein binding
What happens to the drug is it is protein bound?
- it is pharmacologically inactive (the drug is overtaken and is engulfed by a protein)
What are the different things that contribute to drug metabolism?
- phase 1 and phase 2 reactions, michaelis-menton (phenytoin- kinetics are non-linear), genetics, age, disease states, drug interactions
What are the different ways that drugs are excreted?
- renal clearance (filtration, secretion, reabsorption), enterohepatic circulation, biliary clearance
What is the definition of bioequivalence?
methodology of measuring (experimental design, statistical considerations). relative and absolute bioavailability
High molecular weight cannot be given in what route?
Orally
What is the onset of action of inhalation devices?
- rapid onset
IV drugs are suitable for what medications?
- Suitable for large volumes and for irritating substances or complex mixtures, when diluted
- Its valuable for emergency use
- Permits drug titration
- Usually required for high molecular weight protein and peptide drugs
- Not suitable for oily solutions or poorly soluble solutions
What is the absorption pattern of subcutaneous injection?
- prompt, from aqueous solution
- slow and sustained, from repository preparations
Subcutaneous injection is suitable for what medications?
- suitable for some poorly soluble suspensions and for installation of slow release implants
- not suitable for large volumes
- possible pain or necrosis from irritating substances
What is the absorption pattern of intramuscular injections?
- prompt, from aqueous solution
- slow and sustained, from repository preparations
Intramuscular injection is suitable for what medications?
- suitable for moderate volumes, only vehicles, and some irritating substances
- appropriate for self-administration
What is the bioavailability like for oral medications?
- potentially erratic and incomplete
Are ionized drugs able to cross over into the absorption site?
NO - they may require transport proteins to cross
Can hydrophilic drugs pass into the lipid bilayer?
- aquaporins allow water and inorganic ion passage - the majority of drugs are TOO LARGE to fit through.
What is diffusion characteristic of?
- characteristic of particle size, concentration, high to low concentration - its a physical and a chemical event —- it is either a passive or an energy requiring process (only active TRANSPORT)