1. Enzymes 2. Ion Channels 3. Membrane receptors

Chem Exam 4 Flashcards by Laura Chaffin

What is a strong acid?

completely ionizes (breaks into ions)

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List the strong acids (6)

HCl
HBr
HI
HNO3- nitric acid
HClO4- perchloric acid
H2SO4- sulfuric acid

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Strong acids have _____ conjugate bases

weak

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Weak acids have _____ conjugate bases

strong

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List the strong bases (6)

LiOH
NaOH
KOH
CaOH2
SrOH2
BaOH2

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the study of the interactions between a drug and organism

pharmacology

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the study of how a drug affects the
organism

Pharmacodynamics

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the study of how the organism affects the
drug

Pharmacokinetics

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3 Receptor subtypes

Enzymes
Ion Channels
Membrane receptors

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How do drugs bind to their receptors? (4)

Electrostatic interactions (intermolecular forces)
Hydrophobic interactions
Covalent bonds
Stereospecific interactions (enantiomers)

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What is drug affinity?

how well the drug binds to the receptor

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What is drug efficacy?

how well the drug produces its desired effect

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What is drug potency?

comparison of the relative affinity of competing drugs

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Bioavailability

how much of the administered drug is actually
absorbed. (typically used for oral administration)

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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

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Distribution is affected by (6)

*Blood
* Total body water
* Extracellular fluids
* Lymphatic fluids
* Cerebrospinal fluids
* Protein-binding

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Main routes for excretion (4)

Kidneys (majority of drugs)
Feces (unabsorbed drug or metabolites from bile)
Lungs (inhaled anesthetic drugs)
Sweat (not very common)

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What does Lipinski Rule of 5 predict?

Used as a tool to measure a NCE’s potential bioavailability

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What is the max number of hydrogen bond donors and acceptors for Lipinski Rule of 5?

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What are typical hydrogen bond donors?

Thiols*, Amines and alcohols

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What are typical hydrogen bond acceptors?

N,O

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What is the max molecular weight for Lipinski Rule of 5?

< 500 g/mol

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What is the calculated partition coefficient? What should it be for Lipinski Rule?

ratio solubility of water vs oil
< 5

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How many rules can be violated to predict a NCE is non-orally available?

more than one

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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?

1. pH of the solution 2. 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?

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