intro Flashcards
what is biopharmaceutics?
It is the study of the factors influencing the
bioavailability of a drug in man and animals and
the use of this information to optimize
pharmacological and therapeutic activity of drug
products
give examples on the factors that influence bioavailability
1-Chemical nature of a drug (weak acid or weak
base)
2- Inert excipients used in the formulation of a
dosage form (e.g. diluents, binding agents,
disintegrating agents, coloring agents, etc.)
3- Method of manufacture (dry granulation
and/or wet granulation).
4-Physicochemical properties of drugs (pKa,
particle size and size distribution, partition
coefficient, polymorphism, etc.).
what is the goal of biopharmaceutics?
to develop a dosage form that will provide consistent
bioavailability at a desirable rate, which is important for drugs with a narrow therapeutic window
what is the LADME process?
• Liberation
• The release of the drug from its dosage form
(Dissolution)
• Absorption:
• It is defined as the process by which a drug proceeds
from the site of administration to the site of
measurement (usually blood, plasma or serum).
Distribution:
• It is the process of reversible transfer of drug to and
from the site of measurement (usually blood or
plasma).
• Any drug that leaves the site of measurement and
does not return has undergone elimination
Metabolism:
• It is the process of a conversion of one chemical
species to another chemical species.
• Usually, metabolites will possess little or none of the
activity of the parent drug.
Elimination:
• It is the irreversible loss of drug from the site of
measurement (blood, serum, plasma).
• Elimination of drugs occur by one or both of:
• Metabolism
• Excretion.
Excretion
• It is defined as the irreversible loss of a drug in a
chemically unchanged or unaltered form.
• The two principal organs responsible for drug
elimination are the kidney and the liver.
The rate and extent of drug distribution is determined
by?
• How well the tissues and/or organs are perfused
with blood.
• The binding of drug to plasma proteins and tissue
components. bound drugs do not cross membranes
• The permeability of tissue membranes to the drug
molecule.
all of them depend on the physicochemical properties of the drug
give an example on drugs that are specifically concentrated in one or more tissues
• Example: iodine is concentrated by the -thyroid
gland.
• Example: highly lipid soluble compounds are
extensively distributed into fat tissues
give an example on active metabolites
• Procainamide: active metabolite is Nacetyl
procainamide
• Propranolol HCl: active metabolite is 4-
hydroxypropranolol
• Diazepam: active metabolite is
desmethyldiazepam.
what are the sites for metabolism
Liver is the primary route of drug metabolism, other
tissues such as kidney, lung, small intestine, and skin
also contain biotransformation enzymes
what are the organs for excretion?
The kidney is the primary site for removal of a drug in a
chemically unaltered or unchanged form (i.e. excretion) as well as for metabolites.
The lungs, occasionally, may be an important route of
elimination and excretion for substances of high vapor pressure
Another potential route of drug removal is a mother’s milk.
• Although not a significant route for elimination of a drug
for the mother, the drug may be consumed in sufficient
quantity to affect the infant.
what is disposition?
all the processes that occur subsequent to the absorption of the drug.(distribution,metabolism,and excretion)
what are the following
Cmax
Tmax
AUC
MTC
MEC
onset time
Duration of action
• Cmax: the highest plasma drug concentration observed.
• Tmax: the time at which Cmax occurs following administration of an extravascular dose.
• AUC: Area under the curve: It is related to the amount of drug absorbed systemically.
• MTC: Minimum toxic concentration: The drug concentration needed to just produce a toxic effect.
• MEC: Minimum effective concentration: The minimum
concentration of drug needed to produce the desired
pharmacologic effect.
• Onset time: The time required for the drug to reach the MEC.
• Duration of action: The difference between the onset time and the time for the drug to decline back to the MEC.
what is the bioavailability
the rate, and extent to which,the drug reaches the systemic circulation.
property not only of the drug but also of the
dosage form.
should be constant among, batches and brands
measured by AUC (extent) and Cmax(rate and extent)and Tmax (rate)
what is the bioavailability factor
It is the fraction of the dose that is able to gain access to the systemic circulation. It is assessed by means of the AUC and is directlyproportional to Cmax.
what are chemically equivalent drugs
These are two or more drug products that contain equal amounts
of the same therapeutically active ingredient(s) in identical
dosage forms, and have the same chemical form
what is bio equivalence
two or more chemically or
pharmaceutically equivalent products produce comparable
bioavailability characteristics in any individual when
administered in equivalent dosage regimen