Pharmacology L4 Flashcards
How do drugs reach their target tissue
Through the blood
What are the general routes of drug administration
! Oral
! Intravenous
! Intra-arterial
! Intramuscular
! Subcutaneous
! Inhalation
! Topical
! Sublingual
! Buccal
! Rectal
What is ‘First-Pass Hepatic Elimination’
a pass through the liver, which may cause an
inactivation of the drug via biotransformation
What is the time course of drug concentation
Initially, drug conc is at its highest but it starts to decrease as time goes
Time course of drug concentration consists of:
-absorption
-distribution
-elimination
Absorption
Uptake from stomach and intestines into blood
Distribution(α-phase)
Systemic distribution into body tissues
Elimination (β-phase)
Elimination from body by biotransformation and excretion
External and internal barriers of the body to drug absorption
GI-tract barrier
Respiratory tract barrier
Oral mucosa barrier
Skin barrier
Blood-brain barrier
GI tract barrier
The intestinal epithelium with brush border serves as a barrier for orally administered drugs. The brush border contains microvilli that increase the surface area for absorption of nutrients and drugs.
Respiratory tract barrier
Cilia-bearing epithelium in the respiratory tract helps trap foreign particles and prevent them from entering the lungs
Oral mucosa barrier
The non-keratinized squamous epithelium lining the oral cavity provides a barrier for sublingual and buccal drug administration.
Skin barrier
The keratinized squamous epithelium in the skin provides a barrier for transdermal drug delivery
Blood-brain barrier
The pore-lacking CNS endothelia in the blood-brain barrier helps protect the brain from harmful substances.
Drugs may traverse biomembranes by
- Gradient diffusion
- Carrier transport
- Vessicular transport
- Surface receptor
What is gradient diffusion used for
For lipophilic not hydrophilic substances
How does gradient diffusion occur
- Diffusion (passive transport)
- Facilitated diffusion (passive transport)
- Active transport
Diffusion (passive transport)
Is the movement of a solute down a gradient. A transport protein is not needed
Facilitated diffusion (passive transport)
is movement down a gradient with the aid of a transport protein
Active transport
movement against a gradient with the aid of a transport protein
Membrane-associated proteins as drug targets
- integral receptor protein
- ion channel protein
- ion pump protein
Carrier-mediated transport through membranes occur by
transporter proteins
What are transporter proteins
specialized proteins found in the cell membrane that are responsible for transporting drugs into and out of the cell. Transporter proteins function by binding a solute on one side of the membrane and undergoing a conformational change that allows the molecule or ion to be transported across the membrane to the other side.
Types of transporter proteins
-uniporter
-symporter
-antiporter
Uniporter
These transporter proteins transport a single solute in one direction across the membrane
Symporter
transport two or more solutes in the same direction across the membrane.
Antiporter
transport two or more solutes in opposite directions across the membrane.
Receptor-mediated endocytosis
Receptor-mediated endocytosis is a process by which cells take up specific molecules from the extracellular fluid by binding to receptors on the cell surface and transporting them into the cell.
Why is drug binding to plasma proteins like albumin important
since the concentration of the free drug
determines the intensity of the pharmacological effect
Depending on the particular physicochemical properties of a drug, the
distribution of a pharmacological substance will be restricted to the:
-Vasculature Blood
-Extracellular spaces
-Intracellular spaces
-Tissue receptors
What is biotransformation
a protective mechanism of the body to promote the efficient removal of potentially harmful substances
How can biotransformation affect a drug negatively
chemical modification of xenobiotic substances may also cause a
loss of pharmacological potency or biological function of a drug.
Phase I biotransformation reactions
Oxidation; Reduction; Alkylation; Hydrolytic cleavage
Phase II biotransformation reactions
Conjugation reactions with glucoronic acid or sulfuric acid
Excretory kidney function
The chemical derivatives of drugs or chemically unchanged drugs are eliminated in the urine. drugs with a molecular mass of less than 5,000 Da pass through the vascular walls of the glomerular capillaries.
