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Phase 2A: ICS > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

Define pharmacology

A

The study of the effects of the drug

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2
Q

Define pharmokinetics (PK)

A

How the body affects the drug: Absorption, Distribution, Metabolism and Excretion (ADME)

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3
Q

Define pharmacodynamics (PD)

A

How the drug affects the body

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4
Q

What are the 4 main actions of pharmacokinetics

A
  1. ) Absorption
  2. ) Distribution
  3. ) Metabolism
  4. ) Excretion
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5
Q

Describe the process of absorption in pharmacokinetics

A
  • Absorption = the process of transfer from site of administration into the systemic circulation
  • Routes of transmission: oral/intramuscular/topical/inhalational/intravenous/sublingual/intra arterial
  • To be absorbed the drug needs to pass through one membrane minimum
  • They do this via:
  • passive diffusion through the lipid layer
  • diffusion through pores or ion channels
  • pinocytosis
  • carrier mediated process (e.g. ATP-binding cassette)
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6
Q

Give an example of absorption within pharmacokinetics

A
  • E.g oral absorption
  • Advantages: good due to large SA and high blood flow in the small intestines
  • Disadvantages: drugs can be metabolised, so less efficient
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7
Q

What are the main factors that affect the speed of oral absorption?

A
  1. ) First pass metabolism: drugs need to get through the intestinal lumen, intestinal wall, liver and lungs
  2. ) Drug structure and formulation
  3. ) Gastric emptying
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8
Q

Describe the process of distribution in pharmacokinetics

A

Distribution = the process by which the drug is transferred from general circulation to tissues, occurring via passive diffusion across cell membranes

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9
Q

Give an example of distribution in pharmacokinetics

A

IV drugs: initially you have a high plasma concentration. Drugs will quickly enter well perfused tissue and then the drug will enter the less well perfused tissues and lower the plasma concentration

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10
Q

What are some important points on distribution in pharmacokinetics?

A
  • Remember most drugs bind to plasma/tissue proteins. Thus, by binding you will lower the ‘free’ concentration of the drug
  • Distribution is important as it determines the total amount of drug that has to be administered to produce a particular plasma concentration
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11
Q

How do you measure distribution of a drug?

A

Vd: the total amount of drug in body/plasma concentration

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12
Q

What does the rate of distribution for water soluble drugs depend on?

A

The rate of passage across membranes

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13
Q

What does the rate of distribution for lipid soluble drugs depend on?

A

The blood flow to tissues that accumulate the drug

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14
Q

Define clearance

A

The volume of blood or plasma cleared of the drug per unit time

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15
Q

Define metabolism in pharmacokinetics

A

Metabolism = the process where lipid soluble drugs are converted into water soluble molecules

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16
Q

What are the names of the two reactions involved in metabolism in pharmacokinetics?

A
  1. ) Phase 1

2. ) Phase 2

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17
Q

Describe a phase 1 reaction in metabolism

A
  • The drug is transformed into a more polar metabolite
  • This is done by adding a functional group
  • Common example is oxidation (catalysed by p450 enzymes)
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18
Q

Describe what P450 enzymes are

A
  • They are isoenzymes
  • They are present in the smooth endoplasmic reticulum
  • Grapefruit inhibits them
  • Smoking induces them
19
Q

Describe a phase 2 reaction in metabolism

A
  • Involves the formation of a covalent bond between: the drug, and its phase 1 metabolite
  • It is an endogenous substrate
  • End result: a less active drug that can be excreted by the kidneys
20
Q

Define excretion

A

Drugs and metabolites are excreted in:

  • fluids: urine and sweat
  • solids: faeces
  • gases
21
Q

Define antibiotic

A

Antibiotic = an antibacterial drug. Work by binding a target site on bacteria. Semi-synthetic derived of antibiotics are ‘antimicrobials’

22
Q

What does the class of ‘antimicrobials’ include

A
  • antifungal
  • antibacterial
  • anthelminthic
  • antiprotozoal
  • antivirals
23
Q

Define the key mechanisms of actions of antibiotics (what do they block)

A
  1. ) Inhibit protein synthesis
  2. ) Inhibit cell wall synthesis: e.g. beta lactams disrupt the peptidoglycan production by binding covalently to the PBPs-> results in lysis
  3. ) Inhibit nucleic acid synthesis
  4. ) Anti-metabolites
  5. ) Inhibit membrane function
24
Q

Give 4 examples of antibiotics that inhibit cell wall synthesis

A
  1. ) Penicillin: Penicillin V or Amoxicillin
  2. ) Cephalosporins: cephalexin or cefotaxime (use is person has penicillin allergy)
  3. ) Carbapenems: meropenem or entapenem
  4. ) monobactams: aztreonam
  • note: all beta-lactams
25
Q

What is the difference between bacteriostatic and bactericidal antibiotics

A
  • Bacteriostatic: prevents growth of bacteria by inhibiting protein synthesis or dna replication
  • Bactericidal: KILLS bacteria (99% in 24hrs) via cell wall synthesis inhibition
26
Q

Macrolides: action/gram/example

A
  • Action: inhibitor of protein synthesis
  • Used on gram +
  • E.g. clarithromycin
27
Q

Lincosamides: action/gram/example

A
  • Action: inhibitor of protein synthesis
  • Used on gram +
  • E.g. clindamycin: used in cellulitis
28
Q

Tetracycline: action/gram/example

A
  • Action: inhibitor of protein synthesis
  • Used on gram +
  • E.g. doxycycline used in cellulitis
29
Q

Aminoglycosides: action/gram/example

A
  • Action: inhibitor of protein synthesis
  • Used on gram -
  • E.g. gentamicin (IV only) used in UTI/infective endocarditis
30
Q

Quinolones: action/gram/example

A
  • Action: inhibitor of protein synthesis
  • Used on gram -
  • E.g. ciprofloxacin: used in penicillin allergy/UTI/intra-abdominal infection
31
Q

Trimethoprim: action/gram/example

A
  • Action: inhibitor of protein synthesis
  • Used on gram -
  • E.g. in UTI’s
32
Q

Nitrofurantoin: action/gram/example

A
  • Action: inhibitor of protein synthesis
  • Used on gram -
  • E.g. in LOWER UTI
33
Q

Define a cholinergic drug

A

Cholinergic drug = an agent that acts upon the neurotransmitter acetylcholine. The 3 main categories are direct acting, indirect acting: reversible and irreversible

Bit on cholinergic pharmacology:
- Cholinergic receptors are split into two groups: muscarinic and nicotinic
- Muscarinic have:
- M1:couples with Gq to increase Ca2+. In gut.
M2: couples to GI to increase K+. In heart.
M3: couples to Gq to increase Ca2+. In sweat.
M4
M5
- Nicotinic:
- have Nm AND Nn

34
Q

Describe the mechanism of action for a cholinergic drug

A
  • Direct acting: mimic the effects of acetylcholine
  • Indirect acting: work by binding to acetylcholine esterase enzyme (enzyme that breaks down ach to form acetyl and choline) so acetylcholine will build up in the body
35
Q

List examples for cholinergic drugs

A

Direct acting examples:

  • pilocarpine: stimulates salivation and contracts smooth muscle of the iris by facilitating the drainage of aqueous humour (can treat glaucoma)
  • carbachol: decreases intra ocular pressure

Indirect acting examples:
- e.g. edrophonium/neostigmine: used for myasthenia Gravis

36
Q

Define an adrenergic drug

A

Adrenergic drug = stimulate the nerves in your body’s sympathetic nervous system
- Remember: dopamine is a pre-curosir to noradrenaline and adrenaline

37
Q

Describe the mechanism of action for an adrenergic drug

A

Receptors:

  • Alpha 1: increase intracellular calcium: contracts smooth muscle
  • Alpha 2: inhibit cAMP: have mixed effects on smooth muscle
  • Beta 1: raises cAMP: chronotropic + inotropic effects on heart
  • Beta 2: raises cAMP: relaxes smooth muscle
  • Beta 3: raises cAMP: enhances lipolysis/relaxes bladder detrusor muscle
38
Q

List examples of adrenergic drugs

A

1.) Alpha agonists
- cause alpha-1 activation
results in vasoconstriction
- treats nasal congestion

  1. ) Alpha blockers
    - block alpha 1 receptors
    - decrease blood pressure (e.g. doxazosin)
    - Tamsulosin blocks alpha 1a in prostate to treat prostatic hypertrophy
  2. ) Beta agonists:
    - B1 activation increases HR so bigger risk of arrhythmiasB2 activation causes muscle relaxation for treatment of asthma and also delays premature labour
    - Beta agonists cause tachycardia
    - B3 agonists reduce overactive bladder symptoms
  3. ) Beta blockers:
    - E.g. propranalol: blocks beta 1 and beta 2. Slows heart rate
    - Atenolol: beta 1 selective so people don’t wheeze
    - These lower B.P and are used for arrhythmias
    - Benefits: treats angina/M1 prevention/anxiety/high b.p
    - Cons: tiredness/bronchoconstriction/bradycardia
39
Q

Define an analgesic drug

A

Analgesic drugs: relieve pain without causing a loss of consciousness

How does pain work chemically:

  • Get trauma
  • Body produces phospholipase A2 which converts phospholipids in tissues to arachidonic acid
  • COX-2 enzyme will then convert this acid to endoperoxides
  • This is then converted to a range of prostaglandins
  • Prostaglandins cause two things: inflammation and pain transmission
40
Q

Describe the mechanism of action for an analgesic drug

A

1.) NSAID’s: block action of COX-2 so arachadonic acid is not converted into endoperoxides

  1. ) Opiods: act at different opioid receptor sites to block the transmission of severe pain by reducing the amount of neuropeptides and neurotransmitters e.g. substance p and glutamate
    - opioid receptors are G protein coupled receptors and there are 3 subtypes: delta/kapa/new
    - work at the substantial gelatinosa in the dorsal horn of the spinal cord/medulla/thalamus and area of cerebral cortex
41
Q

List examples of analgesic drugs

A
  1. ) NSAIDS: ibuprofen

2. ) Opioids

42
Q

Define adverse drug reactions

A

adverse drug reaction = a response to a drug which is noxious and unintended

43
Q

Define drug interactions

A

When two or more drugs interact with each other. This can lead to unintended side effects

Phase 2A: ICS (3 decks)

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