Chem Exam 4 Flashcards
What is a strong acid?
completely ionizes (breaks into ions)
List the strong acids (6)
- HCl
- HBr
- HI
- HNO3- nitric acid
- HClO4- perchloric acid
- H2SO4- sulfuric acid
Strong acids have _____ conjugate bases
weak
Weak acids have _____ conjugate bases
strong
List the strong bases (6)
- LiOH
- NaOH
- KOH
- CaOH2
- SrOH2
- BaOH2
the study of the interactions between a drug and organism
pharmacology
the study of how a drug affects the
organism
Pharmacodynamics
the study of how the organism affects the
drug
Pharmacokinetics
3 Receptor subtypes
- Enzymes
- Ion Channels
- Membrane receptors
How do drugs bind to their receptors? (4)
- Electrostatic interactions (intermolecular forces)
- Hydrophobic interactions
- Covalent bonds
- Stereospecific interactions (enantiomers)
What is drug affinity?
how well the drug binds to the receptor
What is drug efficacy?
how well the drug produces its desired effect
What is drug potency?
comparison of the relative affinity of competing drugs
Bioavailability
how much of the administered drug is actually
absorbed. (typically used for oral administration)
8 Factors affecting bioavailability include:
*Molecular weight of the drug
* Drug formulation
* Drug stability (especially pH sensitivity)
* First pass metabolism (typically in the liver)
* Blood flow
* Gastric emptying (food slows this process)
* Intestinal motility
* Drug interactions
Distribution is affected by (6)
*Blood
* Total body water
* Extracellular fluids
* Lymphatic fluids
* Cerebrospinal fluids
* Protein-binding
Main routes for excretion (4)
- Kidneys (majority of drugs)
- Feces (unabsorbed drug or metabolites from bile)
- Lungs (inhaled anesthetic drugs)
- Sweat (not very common)
What does Lipinski Rule of 5 predict?
Used as a tool to measure a NCE’s potential bioavailability
What is the max number of hydrogen bond donors and acceptors for Lipinski Rule of 5?
10
What are typical hydrogen bond donors?
Thiols*, Amines and alcohols
What are typical hydrogen bond acceptors?
N,O
What is the max molecular weight for Lipinski Rule of 5?
< 500 g/mol
What is the calculated partition coefficient? What should it be for Lipinski Rule?
ratio solubility of water vs oil
< 5
How many rules can be violated to predict a NCE is non-orally available?
more than one
Functional groups that have been linked to increased toxicity
Thiopenes
Aromatic anilines
Nitroaromatics
Aliphatic halides
Polycyclic aromatic hydrocarbons
T/F: Low MW drugs with high cLogP can easily cross membranes
False; low cLogP
What is cLogP?
calculated partition coefficient
T/F: Potential drug compounds must have either hydrophilic and lipophilic groups
False; must have a mixture
Drug efficacy is directly related to the _______ of the drug at the site of action
concentration
What size of drugs will undergo bulk flow?
< 50 Da
What size of drugs will undergo passive transport?
50-500 Da (must be lipophilic)
What size of drugs will undergo active transport?
> 50 Da (ionized)
Describe Lewis acid vs base
Acid- electron acceptor
Base- electron donor
Describe Bronsted-Lowry acid vs base
Acid- proton donor
Base - proton acceptor
What is the difference between strong acids /bases and weak acids/bases?
Strong acids/bases completely ionize when dissolved in water
Strong acids have _______
Weak acids have ________
weak conjugate bases
strong conjugate bases
Equillibrium favors the formation of
weaker acids
Water is __________. It can act as an acid or base
amphoteric
pH scale is _______ so a change of 1 actually scales to change by a factor of ______
logarithmic
10
What is the pH of 1.2 M solution of acetic acid
ph= 2.39
Calculate the pH of 0.00250 M solution of morphine (Kb = 1.6 x 10 ^ -6)
pH= 9.8
What are buffers?
Solutions that contain a weak acid and its conjugate base or a weak base and its conjugate acid
When do buffers resist change in pH?
When strong acids or bases are added in limited quantity
What is the buffer capacity?
The limit to the amount of acid/base that can be added before the buffer loses its ability to resist change
Blood pH is controlled through which systems in the body?
respiratory and renal
The respiratory system directly impacts the _______
carbonic acid buffer system
The renal system works to remove _______ through the ______
hydrogen ions
kidney
What enzyme is responsible for combining hydrogen ions with bicarb? What is formed?
carbonic anhydrase
carbonic acid
What diffuses from the urine into the PCT?
CO2
Carbonic anhydrase combines _____ and ______ to form carbonic acid inside the PCT
CO2
H2O
Pharmacodynamics can be affected by
Disease, age, and drug interactions
Receptor subtypes for signaling
Membrane receptors
Receptor subtype for transportation
Ion channels
Receptor subtype that’s a catalyst
Enzymes (most common)
What is therapeutic dosing?
Drug concentration based on weight
What is a prodrug?
Convert drugs from inactive state to active form
Common process of metabolism
- hydrolysis (esters, amides, nitriles)
- Redox (CYP450)
What is a normal ClogP?
0-5 (too low = won’t be retained / too high = deposited in fatty tissues)
The majority of local anesthetics are _______
weak bases
What is drug ionization?
The process by which a drug becomes electrically charged in the body
What does the degree of drug ionization affect?
The drug’s ability to be absorbed and distributed throughout the body
Describe ionized drugs
High electrical resistance and low lipid solubility; difficult to pass through cell membranes
Describe unionized drugs
High lipid solubility allowing them to easily diffuse across cell membranes
What kinds of drugs are able to be absorbed better in the stomach?
Acidic drugs
What two factors control drug ionization?
- pH of the solution
- pKa of the drug
Acid strength is _______ and depends on what?
relative
The ability of the group to give up a proton
The larger the Ka the _______
more acidic
(its easier to remove a proton)
The larger the pKa the ______
less acidic
What are the ranges for pKa?
-20 - 60
What is the pKa of water?
16
Describe van der waals
Interaction arising between two non-polar molecules
Weakest of the intermolecular forces
Describe Dipole-dipole interactions
occurs in all polar molecules
Describe hydrogen bonding
Very strong, specialized dipole-dipole interaction
(H bond donors/acceptors)
Describe Ion dipole bonding
Very strong interaction between a full formal charge and a dipole
