Absorption/Distribution Flashcards
What are the 4 end destinations for a free (unbound) drug in circulation?
- Storage in tissue depot (fat depot)
- Site of action (cell receptor)
- Metabolism (liver, lung, GI)
- Excretion (kidney, expiration, sweat, feces)
What are the four types of passive transfer?
- Diffusion
- Filtration and bulk flow
- Endocytosis
- Ion-pair
What cell provides an additional barrier preventing drugs from escaping brain capillaries and entering brain tissue?
Astrocytes
If pH>pK, does the protonated or unprotonated form predominate?
Unprotonated (A- or B)
If pH<pK, does the protonated or unprotonated form predominate?
Protonated (AH or BH+)
In ion trapping, does the drug get trapped on the side with the higher or lower ionized fraction?
Higher
What are the 4 factors involved in deciding the route of administration of a drug?
- Speed of onset
- Duration of effect
- Site of action
- Avoidance of undesirable side effects
Where in the SI is most drug absorbed?
Jejunum
What is the term for drug administration that goes through the GI tract? What are the three specific routes for this type of administration?
Enteral
- Oral (per os)
- Sub-lingual - bypasses liver (ex: nitroglycerin)
- Rectal - 50% bypasses liver (ex: Tylenol, Compazine, Phenergan)
What is the term for drug administration that bypasses GI tract? What are the 7 specific routes for this type of administration?
Parenteral
- Intravenous (iv)
- Intramuscular (im) - Ex: Epinephrine, antibiotics, antipsychotics
- Subcutaneous (sc) - Ex: insulin
- Inhalation - Ex: general anesthetics, asthma drugs
- Topical - Ex: steroid ointments & creams
- Transdermal - Ex: nitroglyerin, nicotine
- Intrathecal (through brain) - Ex: anticancer drugs, antibiotics
What are the two types of drug delivery approaches?
- Timed/Prolonged release preparations (sustained release, controlled release from a resinate)
- Controlled variable rate (electrolytic gas production released from syringe)
Can volume of distribution ever be greater than total body water?
Yes - when drug binds to a storage site, this can happen
What is the effective form of a drug? Free or bound?
Free
What are possible drug storage sites?
Tissue fat, protein, or nucleic acids, or plasma protein (mostly albumin)
