Week1 part 1 Flashcards
What is Pharmacodynamics?
What a drug does to the body
- study of the biochemical, physiologic, and molecular effects of drugs on the body; involves receptor binding
What is a receptor?
- A protein or other substance that binds to an endogenous chemical or drug
- Coupling causes chain of events leading to an effect
Nagelhout, pg. 55
What are the three common properties of a receptor?
- Sensitivity: Drug response occurs from a low concentration. Less receptors is more sensitive to a drug.
- Selectivity: Drug response produced by structurally similar chemicals. (Low selectivity means lookalike drugs can attach, high selectivity means drugs need to be identical to what the receptor wants)
- Specificity: Drug response from a given set of receptors is always the same because the cells themselves determine the response
Nagelhout, pg. 55
Name the forces (from weakest to strongest) that lead to bonds between drugs and receptors
- Van der Waals
- Hydrophobic
- Hydrogen
- Ionic
- Covalent
Nagelhout, pg. 55
True or false:
Receptors are a single type of protein to which an endogenous substance or drug may complex to transmit a signal
False
- several mechanisms/receptor types have been identified
Nagelhout, pg. 55
Name several types of receptor classifications
GABA, Opioid, Alpha, Beta, Acetylcholine, Histamine, pain-related capsaicin
Nagelhout, pg. 56
True or False
Available receptors need to be 100% saturated with drug molecules to exert the desired effect?
False
- Complete saturation of available receptors with drug molecules is not necessary for a desired tissue response to be elicited
- I.E. acetylcholine and its receptor at the neuromuscular junction (Less than 1% of the cell surface binds drug to receptor protein to achieve tissue response)
Nagelhout, pg. 56
What are the 3 main endogenous proteins? What drugs bind with them?
- Albumin: acidic drugs (contains numerous receptor sites)
- a1-Acid glycoprotein**: basic drugs
- B-globulin**: basic drugs
Current understanding of molecular pharmacology suggests that the delay recorded from initial drug administration to the onset of the tissue response is due to what 3 factors?
- Molecular orientation and attachment to the receptor
- Receptor protein conformational change
- Tissue response time
Nagelhout, pg. 56
G protein-coupled receptors (GPCR) utilize ____________ in the process of signal transduction
second messenger pathways
* e.g. cyclic adenosine monophosphate (cAMP) & cyclic guanosine monophosphate (cGMP)
Nagelhout, pg. 56
How do GCPR second messengers lead to a tissue response?
- they regulate enzymes (e.g. protein kinases, phosphatases) involved in ordered sequences or cascades of biochemical reactions
Nagelhout, pg. 56
Many drugs have similar receptor protein compositions and signal transduction processes. What leads to different drug-induced tissue responses?
The primary difference among drug receptor proteins may only be the:
* Selective binding subunits
* Ion species moving through the channel
(e.g. acetylcholine –> sodium ions, GABA –> chloride)
Nagelhout, pg. 56
Specific peptide subunits are ultimately responsible for the pharmacologic properties of what three things?
Specificity
Affinity
Potency
Nagelhout, pg. 56
What is the drug response formula?
D+R<=> (DRC) <=> TR
- Drug (D) combines with receptor (R) to form a drug receptor complex (DRC) that elicits a tissue response (TR)
- derived from law of mass action (rate of reaction proportional to concentrations of reactants)
Nagelhout, pg. 56
The _________ theory states that the magnitude of a drugs effect is proportional to ____________
- occupancy
- number of receptors occupied
(drug receptor interactions have more complexity than this, but this theory serves as a useful background for many pharmacologic concepts)
Nagelhout, pg. 56
What is Pharmacogenetics?
The study of genetically determined variations in response to drugs including –>
- Variations in how a drug is metabolized
- How drugs interact with intended and unintended targets in the body
Nagelhout, pg. 58
What is Population Variability?
- a difference in response to a single drug dosage amongst a patient population
- remember that therapeutic drug doses reflect average doses of a “normal†population of individuals
Nagelhout, pg. 58
What are some parameters that influence Population Variability?
- Age
- Sex
- Body Weight
- Body Surface Area
- Basal Metabolic Rate
- Pathologic State
- Genetic Profile
Nagelhout, pg. 58
The administration of drugs is largely determined by a mean therapeutic dose per _________ or _________ ; the mean is calculated from a previously determined average dose for the “normal” population
- kilogram of body weight
- Body surface area
Nagelhout, pg. 59
The optimal dosing approach for patients when drugs are administered by the intravenous route is _________
- by titration until the desired therapeutic response is attained
Nagelhout, pg. 59
The graded dose response characterizes the change in __________ as ____________ is increased
- measured response
- administered dose
Nagelhout, pg. 59
The graded dose response allows for the comparison of _________ of different drugs with similar MOA
- potency
Nagelhout, pg. 59
What is a quantal dose response?
- The frequency with which a given drug dose produces a desired therapeutic response in a patient population.
Recorded in an all-or-nothing or yes/no fashion
Nagelhout, pg. 60
The lethal dose in 50% of the population is divided by the effective dose in 50% of the population to calculate ___________
- Therapeutic index
Nagelhout, pg. 60