Pharmacology Flashcards by Diego Tejada Cardenas

What’s pharmacokinetics?

Body does to the drug

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Pharmacokinetics processes

Absorption
Distribution
Metabolism
Excretion

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Routes of drug admin

Enteral
Parenteral
Inhalation
topical
Transdermal - patch, onset 15min. I.e: Fentanyl patch

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Types of enteral admin

Buccal/ sublingual
Oral - slowest. Absorbed best in duodenum
Rectal

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Types of parental admin

IV - fastest. Only one 100% bioavailability
IM - Deepest. 5min. Site: upper lateral quadrant of the gluteal muscle
SC - 15min

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What’s bioavailability

Amount of drug that reaches site of action

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Lipophilic & acidic drugs are easier to absorb. TRUE/FALSE

True.

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What’s “hepatic 1st pass effect”?

Drug gets metabolized in the liver - through the Hepatic portal syst- an amount will become inactive

Only PO and rectal will pass this pathway. I.e: Pen G- completely inactive if PO - best route: IV/IM

> H < bioavailability

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What are the absorption mechanisms?

Passive transfer -no energy
Active transport

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Types of passive transfer

Simple passive diffusion - gradient. Hydrophobic/Lipophilic/non-ionized
Filtration - Hydrophilic/Lipophobic/ionized
Facilitated diffusion - carrier-based

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Types of active transport

Needs ATP
Against gradient
I.e: Glucose
Needs carrier

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Osmosis

Similar to filtration

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lipid-soluble compounds get through BBB? T/F

True
Non-ionized drugs have higher lipid solubility
I.e: Thiopental, ultra-short barbiturate

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Factors affecting distribution

Rate of blood flow

Protein binding - albumin (plasma protein) highest ability to bind to drugs - < distribution

Permeability - leaky capillary >distribution. In BBB <distribution

Gastric emptying time

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> blood flow >concentration of a drug?
T/F

True.
Most important factor
I.e: brain, kidneys, liver

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What’s bio transformation of a drug?

Lipophilic to lipophobic
Active to inactive
It gets easily excreted by kidneys

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Types of biotransformation

Inactivation

Formation of active metabolite from active drug. I.e: Digitoxin - Digoxin

Activation of inactive drug - Prodrugs. I.e: Levodopa (inactive) - Dopamine (active)

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Where does Phase I rx occurs and kind of rx?

Liver - Hepatocytes - CYP450 (Cytochromes) system
Oxidation, reduction, hydrolysis

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Which cytochrome causes genetic polymorphism

CYP2D6
Rapid metabolizer - < therapeutic effect. I.e: Codeine
Slow metabolizer - > toxicity

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Examples of CYP450 inducers

Rifampicin
Phenytoin
Carbamazepine
Chronic alcohol

If taken w/Warfarin - > risk of clotting

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Examples of CYP450 inhibitors

Grapefruit juice
Ketoconazole (all azoles)
Cimetidine (heartburn)
Acute alcohol

If taken w/Warfarin - risk of bleeding

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Where does Phase II rx occurs and kind of rx?

Liver and kidney
Rx: Conjugation rx like:
Glucuronidation - glucuronide
Acetylation
Sulfation

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Sites for drug of elimination

Kidneys and liver
Also lungs - Halothane, N2O , bile - cat ionic, anionic, steroid-like , feces

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Factors affecting renal excretion

GFR - plasma protein bound drug isn’t filtered

Kidney tubular reabsorption - pH. I.e: ASA (weak acid) easily reabsorbed in acid conditions

Active secretion
Changes: [plasma protein/binding]
Blood flow
#functional nephrons, renal disease
Volume of distribution

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Types of drug clearance/elimination

Zero-order 1st-order

How is the elimination in each type? (Zero/1st order)

Zero order - linear. I.e: alcohol, phenytoin, ASA (toxic) 1st order - exponential. Most drugs

What’s a drug half life and how many does it take to eliminate it from the body

Time required [drug] to decrease by 50% 4-5 half lives

What’s therapeutic index

How safe a drug is Comparison Therapeutic & toxic effect Lethal dose for 50% of animals to the effective dose for 50% of animals

Formula for Therapeutic index

Ti = LD50 / ED50 LD - lethal dose ED - effective dose

What’s the therapeutic window

Range Desired/ adverse response Narrow therapeutic window >monitoring >risk of side effects

What are the intrinsic activities in pharmacodynamics

Agonist Antagonist Agonist-antagonist

What’s pharmacodynamics?

What the drug does to the body

Types of Agonist intrinsic activities

Full Agonist - full response Partial Agonist - partial response

What’s an agonist drug? And examples

Drug bonds yo receptor and mímica effect of agent/neurotransmitter NE, EPi, Ventolin, Albuterol

What’s an antagonist drug? Examples

Drug binds to receptor and prevents effect to happen Atropine, Benadryl

Type of antagonist

Competitive - binds are weak. >agonist = response Non-competitive - binds too strong. > agonist = No response

What’s an agonist-antagonist

Acts as both. I.e: Opiods

What’s efficacy

#receptors for max response

What affects the efficacy of a drug?

Affinity - how strong drug binds to receptor Intrinsic activity - how strong it can produce desire effect Drug w/both has high efficacy

What’s potency?

Strength

Important factors determining appropriate dosage of a drug?

MH Age Weight

Potency >Affinity T/F

True

Drug effects?

Additive - combination 2 drugs = No enhancement Cumulative - >drug = > [drug] achieved Synergistic - combination 2 drugs = > effect

Drugs adverse rx

Toxicity- excessive dosage of drug for pt Allergy - immune rx Side effect - rx within therapeutic window Idiosyncratic- unusual, unpredictable rx Teratogenicity- fetal abnormalities

Drug abuse

Can result in addiction

Tolerance

Chronic response >dose

Physical/psychological dependence

Physical - continued use of drug to avoid withdrawals Psychological - repeated use of a drug w/o increase dosage

Perception of acute and chronic pain involves the dame regions of the brain (CNS) T/F

True

Dimensions of pain

Sensory - location, intensity, quality Affective - emotions

Categories of pain

Somatic - periodontal, alveolar Visceral - pulpal

Criteria when selecting analgesic

Severity of pain Age Current meds Pregnancy

Which intensity of pain rx Acetaminophen

Mild- mod

Mechanism of action acetaminophen

Inhibits CNS cyclooxygenase

Action of acetaminophen

Analgesic Antipyretic

Acetaminophen antidote

NAC - N-acetylcysteine

Reason acetaminophen is rx to pt w/ hx ulcers and bleeding disorders

Doesn’t affect inflammatory response Platelets function Coagulation pathway

Max dose for adult and kids /day

Adult - 4gr/day * in alcoholics 2gr/day Kids - 2.6gr/day (75mg/kg)

What condition can increase risk of hepatotoxicity and lead to renal toxicity

Pt w/liver dysfunction (cirrhosis, chronic alcoholism) Is not a contraindication is this pt

Contraindications of Acetaminophen

Allergy Relative contraindications: - hepatic/renal dysfunction - alcohol abuse - warfarin

Side effects of Acetaminophen

Headache Sweating Nausea/vomiting Rash Abdominal pan Dark urine