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Medicine > Bonus drugs - antibiotics, analgesics etc. > Flashcards

Bonus drugs - antibiotics, analgesics etc. Flashcards

1
Q

how does N-acteylcysteine work as an antidote to paracetamol overdose?

A

in therapeutic doses, paracetamol is metabolised mainly by conjugation with glucuronic acid and sulfate, with a small amount converted to a hepatotoxic metabolite - normally quickly detoxifed by conjugation with glutathione.
in paracetamol overdose, the body’s supply of glutathione is overwhelmed, toxic produce begins to damage the liver.
acetylcysteine works by replenishing the body’s supply of glutathione to breakdown the paracetamol.

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2
Q

how does activated charcoal work as a poison antidote?

A

molecules are adsorbed onto the surface of the charcoal due to Van der Waals forces as they travel through gut - reduced absorption.
can also increase elimination of some poisons - multiple doses maintain a steep concentration gradient encouraging diffusion of the poison out of the circulation.

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3
Q

how does naloxone act as an opiate antidote?

A

binds to opioid receptors, acting as a competitive antagonist - naloxone will displace the opioid from the receptors, reversing its effects.

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4
Q

describe the mechanism of action of paracetamol

A

weak COX2 inhibitor - involved in prostaglandin metabolism.

in CNS, COX inhibition increases the pain threshold.

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5
Q

name some weak opioids and describe their mechanism of action

A

tramadol, codeine, dihydrocodeine.
metabolised in liver to produce small amounts of morphine - agonist of opioid mu-receptors, producing the analgesic effect.

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6
Q

name some strong opioids and describe their mechanism of action

A

morphine, oxycodone.

activation of mu-receptors in CNS - reduces neuronal excitability and pain transmission.

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7
Q

give some examples of NSAIDs and describe their mechanism of action

A

ibuprofen, naproxen, etoricoxib, diclofenac.

inhibit synthesis of prostaglandins from arachidonic acid by inhibiting COX.

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8
Q

what are the main side effects of NSAIDs?

A

GI ulcers/bleeding.

renal impairment.

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9
Q

name some systemic corticosteroids.

A

prednisolone, hydrocortisone, dexamethasone.

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10
Q

how do systemic corticosteroids work?

A

bind to cystolic glucocorticoid receptors, which translocate to the nucleus where they regulate gene expression.
up-regulate anti-inflammatory genes, down-regulate pro-inflammtory genes (e.g. cytokines, TNF-alpha).

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11
Q

what is the risk of withdrawing steroids suddenly?

A

Addisonian crisis with cardiovascular collapse.

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12
Q

describe how oestrogens and progesterones are used for contraception

A

they both exert negative feedback on LH and FSH release - used to suppress these hormones, and thus suppress ovulation.

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13
Q

give some indications of adrenaline

A

cardiac arrest.

immediate management of anaphylaxis.

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14
Q

describe the mechanism of action of adrenaline

A

potent agonist of alpha 1+2 and beta 1+2 adrenoreceptors - sympathetic effects:
vasoconstriction, increased HR, force and excitability, vasodilation of vessels supplying heart and muscles.
suppression of inflammatory mediator release from mast cells.

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15
Q

to what class of antibiotics do gentamicin and streptomycin belong?

A

aminoglycosides

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16
Q

name 2 aminoglycosides

A

gentamicin, streptomycin, amikacin

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17
Q

give 2 indications for use of aminoglycosides

A 
severe infections, particulary due to Gram-ve anaerobes (incl. Pseudomonas).
severe sepsis.
pyelonephritis + complicated UTI.
biliary sepsis.
endocarditis.
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18
Q

describe the mechanism of action of aminoglycoside antibiotics

A

BACTERICIDAL.

bind irreversibly to bacterial ribosomes and inhibit protein synthesis.

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19
Q

list 2 antifungal drugs

A

nystatin, clotrimazole, fluconazole, ketoconazole.

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20
Q

how does nystatin work against fungi?

A

bind to ergosterol in fungal cell membranes, creating a polar pore which allows intracellular ions to leak out of the cell - kills/slows growth of fungi

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21
Q

how do azoles (ketoconazole, clotrimazole and fluconazole) work against fungi?

A

inhibit ergosterol synthesis, a component of cell membrane - so impair cell membrane synthesis, cell growth and replication.

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22
Q

give 2 examples of cephalosporin/carbapenem antibiotics

A

cephalosporins - cefuroxime, cefalexin, cefotaxime,

carbapenems - imipenem, meropenem, ertapenem

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23
Q

what is an indication for oral cephalosporins?

A

second + third line treatment options for UTI/resp tract infection

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24
Q

what is an indication for IV cephalosporins and carbapenems?

A

very severe/complicated infections, or ones caused by antibiotic resistant organisms.

very broad spectrum.

25
Q

how do cephalosporins/carbapenems exert an antibiotic effect?

A

beta-lactam ring (like penicillins) - inhibit enzymes responsible for cross linking peptidoglycans in bacterial cell walls, weakening them and preventing maintenance of an osmotic gradient - cell swelling and lysis.

26
Q

do cephalosporins have a particular gram -ve or +ve action?

A

gram -ve

27
Q

name 2 macrolides

A

clarithromycin, erythromycin, azithromycin.

28
Q

what class of antibiotics do clarithromycin, erythromycin and azithromycin belong to?

A

macrolides

29
Q

give some indications of macrolide antibiotics

A

generally, as an alternative to penicillins in allergic patients.

in severe penumonia to cover atypical organisms (Legionella pneumophilia, Mycoplasma pneumoniae).

eradication of H pylori with a PPI and amoxicillin or metronidazole.

30
Q

how do macrolide antibiotics work?

A

BACTERIOSTATIC.
inhibit bacterial protein synthesis, binding to a subunit of the bacterial ribosome and blocking translocation, preventing production of long polypeptides.

31
Q

how does bacterial resistance to macrolides develop?

A

ribosomal mutations - common.

32
Q

give some indications of metrondiazole.

A

treatment of infections due to anaerobic bacteria.
antibiotic associated colitis caused by C diff (gram+ve).
dental abscess/aspiration pneumonia due to gram-ve anaerobes.
protozoal infections incl trichomonal vaginal infections and giardiasis.

33
Q

describe the mechanism of action of metronidazole

A

enters bacterial cells by passive diffusion.
aerobic bacteria are unable to reduce it, so metronidazole can only act on anaerobes/protozoa.

reduction of metronidazole generates a free radical which binds to DNA, reducing synthesis - widespread damage, DNA degradation and cell death.

34
Q

give some indications for penicillins

A 
streptococcal infection incl tonsilitis, pneumonia, endocarditis and skin/soft tissue infections.
clostridum infection (tetanus).
meningococcal infection (meningitis, septicaemia).
35
Q

how do penicillins work?

A

inhibit the enzymes responsible for cross-linking peptidoglycans in bacterial cell walls - weakens the walls, results in uncontrolled entry of water - cell swelling, lysis and death.
contain beta lactam ring - side chains determine the antimicrobial spectrum.

36
Q

how does resistance to penicillin develop?

A

bacteria start making beta lactamase - breaks down beta lactam ring.

37
Q

give some indications for piperacillin with tazobactam?

A

strong penicillin.
reserved for severe infection, with broad spectrum of potential pathogens, abx resistance likely or immunocompromised patient.

38
Q

describe the special characteristics of piperacillin and tazobactam that allow them to be used to fight more/stronger infections than standard penicillins

A

piperacillin - beta lactam side chain has been converted to a form of urea which improves affinity to penicillin bind proteins, increasing spectrum of activity to include pseudomonas aeruginosa.

tazobactam - beta lactamase inhibitor, so allows activity against beta lactamase producing bacteria e.g. Staph aureus

39
Q

which penicillin can be used against Pseudomonas aeruginosa?

A

piperacillin + tazobactam.

40
Q

name a broad spectrum penicillin

A

amoxicillin, co-amoxiclav, ampicillin

41
Q

give indications for broad spectrum penicillins

A

empirical treatment of pneumonia, UTIs.
H pylori eradication.
combination treatment for HAIs.

42
Q

what is the “clav” of co-amoxiclav?

A

clavulanic acid - beta lactamase inhibitor

43
Q

what makes amoxicillin a broad spectrum antibiotic?

A

has an amino group side chain on the beta lactam ring that increases its activity against aerobic Gram negative bacteria.

44
Q

name a penicillinase resistant penicillin

A

flucloxacillin - acyl side chain, protects its beta lactam ring from beta lactamases

45
Q

name a tetracyclic antibiotic

A

doxycycline, tetracycline

46
Q

give 2 indications for tetracyclics

A

acne vulgaris.
lower resp tract infections - infective exacerbations of COPD, pneumonia, atypical pneumonia.
chlamydia infection incl. PID.

47
Q

how do tetracyclics work?

A

inhibit bacterial protein synthesis by binding to a ribosomal subunit - prevents bacterial growth.
broad spectrum.

48
Q

how might some bacteria develop resistance to tetracylics?

A

acquire a pump that allows the bacteria to pump the tetracylines out of the cell

49
Q

what antibiotic is the first choice for uncomplicate UTIs?

A

trimethoprim

50
Q

what is the indication for co-trimoxazole?

A

prevention and treatment of pneumocystis pneumonia in people with immunosuppression

51
Q

how does trimethoprim work?

A

inhibits bacterial folate synthesis, slowing bacterial growth as they need folate for DNA synthesis.
there’s a lot of resistance to this drug.

52
Q

give some indications of vancomycin

A

treatment of gram +ve infection e.g. endocarditis - where infection is severe/penicillin resistant.
as part of combo treatment of meningitis.
2nd line for antibiotic associated colitis due to C diff.

53
Q

how does vancomycin work?

A

inhibits growth and cross linking of peptidoglycan chains, inhibiting synthesis of the cell wall of gram+ve bacteria.

54
Q

give an example of a quinolone

A

ciprofloxacin, monifloxacin, levofloxacin

55
Q

what class of antibiotic is ciprofloxacin?

A

quinolones

56
Q

what is the only ORAL antibiotic in common use for Pseudomonas aeruginosa?

A

ciprofloxacin.

piperacillin/tazobactam is IV!

57
Q

how do quinolones work?

A

kill bacteria by inhibiting DNA synthesis, particularly active against aerobic gram -ve bacteria.

58
Q

how do quinines work against malaria?

A

rapid killing of P.falciparum parasites in schizont stage in the blood.

Medicine (14 decks)

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