Pharmacology Flashcards Preview

Step1 > Pharmacology > Flashcards

Flashcards in Pharmacology Deck (60)
Loading flashcards...
1
Q

Pharmacokinetics

A

The effect of the body on the drug

ADME:
Absorption, distribution, metabolism, excretion

2
Q

Pharmacodynamics

A

The effects of the drug on the body

Includes drug efficacy, drug potency, drug toxicity

3
Q

Bioavailability (F)

A

Fraction of administered drug that reaches systemic circulation unchanged

For an IV dose, F = 100%

Orally F typically <100% due to incomplete absorption and first-pass metabolism

4
Q

Volume of distribution Vd

A

Theoretical volume occupied by the total absorbed drug amount at the plasma concentration measured

Vd = amount of drug / plasma drug concentration

Low Vd: drug in Vd
Medium Vd: drug in ECF
High Vd: drug in all tissues including fat

5
Q

Half life T1/2

A

Time required to change the amount of drug in the body by 1/2 during elimination

Property of ONLY first-order elimination

Drug infused at a constant rate takes 4-5 half lives to reach steady state

T1/2 = (0.693 x Vd) / Clearance (CL)

6
Q

Clearance CL

A

The volume of plasma cleared of drug per unit time.

Clearance may be impaired with defects in cardiac, hepatic, or renal function

CL = rate of elimination / plasma drug concentration

7
Q

Dosage calculation

A

Loading dose = (Cp (target concentration) x Vd ) / F
Maintenance dose = (Cp x CL x tau (dosage interval) ) / F

In renal or liver disease, maintenance dose decreases but loading dose is usually unchanged

8
Q

Zero order elimination

A

Rate of elimination is constant regardless of drug concentration

Concentration decreases linearly w time

Ex: phenytoin, ethanol, aspirin

9
Q

First order elimination

A

Rate of elimination is directly proportional to the drug concentration

Concentration decreases exponentially w time

10
Q

Urine pH and drug elimination

A

Ionized species are trapped in urine and cleared quickly while neutral ones are often reabsorbed

Weak acids: aspirin, methotrexate, trapped in basic environment, add bicarb for overdose

Weak bases: amphetamines, trapped in acidic environment, add ammonium chloride for overdose

11
Q

Drug metabolism

A

Phase I: reduction, oxidation, hydrolysis with cytochrome p450, usually yields slightly polar, water-soluble metabolites often still active

Phase II: conjugation (glucuronidation, acetylation, sulfation) usually yields very polar, inactive metabolites (renal excreted)

Geriatric patients often lose phase 1 before phase 2

12
Q

Efficacy

A

Maximal effect a drug can produce

High efficacy drug classes are analgesic medications, antibiotics, antihistamines

Partial agonists often have less efficacy than full agonists

13
Q

Potency

A

Amount of drug needed for a given effect

Increased potency usually means increased affinity for a certain receptor

Highly potent drugs include chemotherapeutic drugs, antihypertensives, and lipid lowering drugs

14
Q

Competitive antagonist

A

No change in efficacy but decreases potency of original drug

Efficacy is overcomes by increasing the concentration of original agonist substrate

15
Q

Noncompetitive antagonist/irreversible competitive antagonist

A

Decreases efficacy.

Cannot be overcome by increasing concentration of original agonist substrate

16
Q

Partial agonist

A

Acts at the same site as full agonist, but with lower maximal efficacy.

Potency can vary compare to full agonist depending on concentration and type

17
Q

Nicotinic Ach receptor

A

Ligand gated Na/K channels

Nn found in autonomic ganglia

Nm found in neuromuscular junction

18
Q

Muscarinic Ach receptor

A

G protein coupled receptors that usually act through 2ndary messengers

5 subtypes: M1,2,3,45

19
Q

Alpha1 receptor

A

Sympathetic

Increase vascular smooth muscle contraction
Increase pupillary dilator muscle contraction
Increase intestinal and blade sphincter muscle contraction

20
Q

Alpha2 receptor

A

Sympathetic

Decrease sympathetic outflow
Decrease insulin release
Decrease lipolysis

21
Q

Beta1 receptor

A

Sympathetic

Increase heart rate
Increase heart contractility
Increase renin release
Increase lipolysis

22
Q

Beta2 receptor

A

Sympathetic

Vasodilation
Bronchodilation
Increase heart rate
Increase heart contractility
Increase insulin release
Decrease uterine tone
Increase aqueous humor production
23
Q

M1

A

Parasympathetic

CNS
Enteric nervous system

24
Q

M2

A

Parasympathetic

Decrease heart rate
Decrease contractility of atria

25
Q

M3

A

Parasympathetic

Increase exocrine gland secretions
Increase gut peristalsis
Increase blade contraction
Increase pupillary sphincter muscle contraction
Ciliary muscle contraction for accomondation

26
Q

D1

A

Dopamine

Relaxes renal vascular smooth muscle

27
Q

D2

A

Dopamine

Modulates transmitter release, especially in brain

28
Q

H1

A

Histamine

Increase nasal and bronchial mucus production
Increase vascular permeability

29
Q

H2

A

Histamine

Increase gastric acid secretion

30
Q

V1

A

Vasopressin

Increase vascular smooth muscle contraction

31
Q

V2

A

Vasopressin

Increase water permeability and reabsorption in the collecting tubules of kidney

32
Q

Bethanechol

A

Cholinergic agonist

Activates bowel and bladder smooth muscle, resistant to AChEsterase

For postoperative ileus, neurogenic ileus, and urinary retention

33
Q

Carbachol

A

Cholinergic agonist

For glaucoma and relief of intraocular pressure

34
Q

Pilocarpine

A

Cholinergic agonist

Resistant to AChE

Potent stimulator of sweat, tears, and saliva
Treatment for open angle and close angle glaucoma

35
Q

Neostigmine

A

Anti-AChE

Increases ACh

For posteroperative and neurogenic ileus and urinary retention, myasthenia gravis

36
Q

Pyridostigmine

A

Anti-AChE

Increase ACh

For myasthenia gravis, does not penetrate CNS

37
Q

Physostigmine

A

Anti-AChE

Increase ACh

Penetrates CNS, treats anticholinergic toxicity (atropine overdose)

38
Q

Donepzil, rivastigmine

A

Anti-AChE

Increase ACh

For Alzheimer disease

39
Q

AChE inhibitor poisoning

A

Too much cholinergics

Often due to organophosphates, such as components of insecticides, that irreversibly inhibit AChE

DUMBBELSS:
Diarrhea
Urination
Miosis
Bronchospasm
Bradycardia
Excitation of skeletal muscle and CNS
Lacrimination
Sweating
Salivation

Antidote: atropine (competitive inhibitor) + pralidoxinme (regenerates AChE if used early)

40
Q

Atropine

A

Muscarinic antagonist

Blocks DUMBBELSS
Also used to treat bradycardia

Toxicity: too much anticholinergic
hot as hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter

Can cause acute angle glaucoma in elderly

41
Q

Benztropine

A

Muscarinic antagonist

Used to treat Parkinsons

42
Q

Ipratropium

A

Muscarinic antagonist

Used to treat COPD and asthma

43
Q

Oxybutynin

A

Muscarinic antagonist

Used to reduce urinary urgency

44
Q

Glycopyrrolate

A

Muscarinic antagonist

Used to reduce airway secretions and prevent peptic ulcers

45
Q

Epinephrine

A

Sympathomimetic

Beta > alpha

Treat anaphylaxis, open angle glaucoma, asthma, hypotension

Alpha effects become predominate effect at high dose

46
Q

Norepinephrine

A

Sympathomimetic

Alpha1 > alpha2 > beta 1

Treat hypotension

47
Q

Dopamine

A

Sympathomimetic

D1=D2 > beta > alpha

Treat unstable bradycardia, heart failure, shock

48
Q

Dobutamine

A

Sympathomimetic

B1 > B2,alpha

Treat heart failure, for cardiac stress test

49
Q

Phenylephrine

A

Sympathomimetic

A1 > A2

Treat hypotension, rhinitis (decongestant)

50
Q

Albuterol, salmeterol

A

Sympathomimetic

B2 > B1

Asthma, COPD

51
Q

Amphetamine

A

Indirect general sympathetic agonist, reuptake inhibitor, release stored catecholemines

Treat narcolepsy, ADHD

52
Q

Ephedrine

A

Indirect general sympathetic agonist, release stored catecholemines

Treat nasal congestion, urinary incontinence, hypotension

53
Q

Cocaine

A

Indirect general sympathetic agonist, reuptake inhibitor

NEVER give beta blocker if cocaine intoxication is suspected

54
Q

Clonidine

A

Sympatholytic (alpha2 agonist)

Treat hypertenisve urgency, ADHD

Toxicity: CNS depression, bradycardia, hypotension, respiratory depression

55
Q

Methyldopa

A

Sympatholytic (alpha2 agonist)

Treat hypertension in pregnancy (only one safe in pregnancy)

Toxicity: hemolytic anemia, SLE-like symptoms

56
Q

Phenoxybenzamine

A

Alpha blocker, irreversible

Treat pheochromocytoma to prevent catechlolamine crisis

57
Q

Phentolamine

A

Alpha blocker, reversible

Give to pts on MAO inhibitor if they eat tyramine-containing food

58
Q

Prazosin, tamsulosin

A

Alpha 1 blocker

Treat urinary symptoms of BPH

59
Q

Mirtazapine

A

Alpha 2 blocker

Treat depression

60
Q

Beta blockers

A

Decrease heart rate/contractility, resulting in decreased O2 consumption –> angina

Decreases MI mortality

Decreases AV conduction velocity –> prevent SVT

Decrease cardiac output and renin secretion –> HTN

Decreases aqueous humor secretion –> glaucoma (timolol)

Toxicity: impotence, bradycardia, AV block, seizures, sedation

Avoid in cocaine users

B1 selective block: atenolol, metoprolol
Non selective alpha block: propanolol
Non selective alpha and beta block: labetalol, carvedilol