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Biopharmaceutics
Your worst nightmare.
So what is "biopharmaceutics"?
*Biopharmaceutics: science focused on the
relationship between the physicochemical
properties of a drug in a dosage form and
observed therapeutic response after
administration.
WHAT THE !@#$
DOES THAT
MEAN?!
• And so I've put up another more human definition!
• The study of the chemical and physical
properties of drugs, their components, their
activities, and their relationships in/with
living organisms.
• http://www.youtube.com/watch?v=mp93n
PUzHqM
So...what is this REALLY about?????
• Biopharmaceutics studys the factors influencing the
presence of drug at the site of absorption and the transfer
of the dissolved drug across biological membranes into the
systemic circulation
• Using biopharmaceutics, we can apply the knowledge
of drug release and transport across biological
membranes to obtain & predict efficacious effects
from a product administered to a patient.
Con't
• In general, biopharmaceutics involves factors that influence the:
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protection and stability of the drug within the product;
the rate of drug release from the product;
the rate of dissolution of the drug at the absorption site; and
the availability of the drug at its site of action.
Biopharmaceutics Classification System
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Class I-high permeability, high solubility
Class II-high permeability, low solubility
Class III-low permeability, high solubility
Class IV-low permeability, low solubility
• Using the knowledge of biopharmaceutics, we can learn that
biological response:
– Is expresssed as alteration of biologic process existing before drug was
administered, like the response from the immune system before any
drugs/medications are taken.
– Its response magnitude is related to drug concentration achieved at
receptor site (the point of attachment to cell membranes for viruses,
hormones, or other specific molecules).
– The observed effect of drug from a dosage form is equal to the
inherent pharmacological activity of the drug + its ability to reach the
receptor site in appropriate concentration.
Con't
• Drug tolerance is the body's ability to adapt to the
presence of the drug, in which the magnitude of the
body's response to a particular drug depends on two
factors:
– Concentration of drug at site of action
– Sensitivity of the receptor site
Overall, the intensity and duration of the effect of
drugs depend on the biological response +
amount of dosage.
More Spectific Factors Influencing the Time Course
of a Drug!
• The physical/chemical properties of the drug
• Type of dosage form of the drug
• Composition and method of manufacture of the dosage
form
• Size of the dose and frequency of administration of the
dosage form
• Site of absorption of the administered drug
• Co-administration of other drugs
• Type of food taken by the patient
• The disease state of the patient that may effect drug
absorption, distribution and elimination of the drug
• Age of patient
• Genetic composition of the patient
Pharmacokinetics
• Pharmacokinetics - the study
of the movement of drug in
the body and how the body
cooperates with the drug.
Con't
• Pharmacokinetics mainly focuses on:
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Absorption
Distribution
Metabolism
Elimination/excretion
Bioavailability
• Bioavailability- the transfer of
drug from its site of
administration into the body
system; manifested by
appearance in general
circulation. It is characterized
by the rate of transfer and the
total amount transferred.
Factors Influencing Drug Absorption-Physiological Factors
• Refers to the nature of the cell membrane:
– Semi-permeable: permits only water, selecte small
molecules, and lipid-soluble molecule. Highly charged
molecules and large molecules (proteins, protein-bound
drug) will not cross.
– Membrane availability (of space, pores, etc.)
– Gastrointestinal passages
The Gastrointestinal Tract
Factors Influencing Drug Absorption--
Physicochemical Factors
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Surface area of the drug
Crystal or amorphous form
Salt form
State of hydration
Solubility
Factors Influencing Drug Absorption--Dosage
Form Factors
• The route of administration
• The inert ingredients (diluents, binders, disintegrants,
suspending agents, coating agent, etc.)
• Type of dosage form (tablet, capsule, solution,
suspension, suppository, etc.)
Biomembranes
• Biopharmaceuticals regard a lot about
biomembranes, so what are they?
• Biomembranes include and limited to:
– Blood-brain barrier
– Renal tubules
– Blood capillaries and renal glomerular
membranes
– Placental barrier
Innovation in Biopharmaceutics
• "Recently, new production methods have been developed
involving plants such as carrot cells, tobacco and rice seeds that
are able to cost-effectively and safely produce
biopharmaceuticals. A recent plant shut-down at Genzyme
highlights the concern of conventional methods that use animal
cells and animal components in biomanufacturing because of the
risk of adventitious prion and viral pathogens of animal origin.
This shut-down led to drug product shortages and helped
advance the approval of a plant-produced alternative to
Cerezyme" (Biotechnology in the Global Economy, ota.fas.org).
JOBS!!!
• Biopharmaceuticals is one of those majors that has a
pretentiously fancy name so it attracts everyone to take
it. Just kidding. Jobs that involve biopharmaceuticals
include:
– Literally EVERYTHING that involves both chemistry and
biology, like anesthesiologist, oncologist, dermatologist,
physican, surgeon, and SO MANY MORE.
– Many sales and managing jobs are available, including
pharmacist, biostatistician, clinc manager, drug salesperson, and
SO MANY MORE.
– http://www.salary.com/careers/layouthtmls/crel_narrowbrie
f_HC04.html