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mp321 > week 2 + 3 > Flashcards

week 2 + 3 Flashcards

1
Q

examples of beta lactams

A

penicillin, carbapenem, cephalosporin, monobactam

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2
Q

what do beta lactam antibiotics inhibit?

A

inhibit the synthesis of the bacterial peptidoglycan by inhibiting the action of cross-linking enzymes (PBPs).

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3
Q

how can stability of penicillin in acidic medium be increased

A

. Attaching electronegative groups minimizes neighboring group attack on the β-lactam carbonyl. (The carbonyl is protected). nucleophilic attacks in the acidic medium prevented.

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4
Q

cephalosporins are a group of ___ spectrum antibiotics that resemble penicillin

A

broad

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5
Q

streptococcus gram positive or negative

A

gram positive

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6
Q

e coli gram negative or positive

A

gram negative

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7
Q

purpose of streaking

A

allows to see distinct colonies on an agar plate

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8
Q

polyenes, give examples

A

bind directly with ergosterol in the cell membrane causing leakage and cell death. examples - amphotericin B, Nystatin

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9
Q

azoles (imidazole and triazole), give examples

A

imidazoles- clotrimazole, miconazole, econazole
triazoles- fluconazole, voriconazole, itraconazole.
comeptitively inhibit the lanosterol enzyme involved in ergosterol biosynthesis.

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10
Q

echinocandins, give examples

A

non-competitively inhibit β-1, 3-D-glucan biosynthesis in cell wall causing cell lysis and death. example- caspofungin

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11
Q

allyamines, give example

A

Inhibit squalene epoxidase required for ergosterol biosynthesis. examples terbinafine

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12
Q

what is low bioavailability caused by

A

high logP values and being bound to plasma proteins.

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13
Q

how does clotrimazole work ?

A

inhibits fungi from producing ergosterol - an essential part of fungal cell membranes. this causes holes in the fungal cell membrane.

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14
Q

what makes clotrimazole available for topical application?

A

positive logP. the drug will be able to permeate te stratocornellium of the skin, and to the fungal cells.

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15
Q

clotrimazole pka

A

5-6

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16
Q

HIV viral replication

A

1- fusion of HIV to the host cell surface
2- HIV RNA, reverse transcriptase, integrase and other viral proteins enter the host cell.
3-Viral DNA formed by reverse transcription
4-Viral DNA is transported across the nucleus and integrates into the host DNA.
5- New viral RNA is used as genomic RNA and used to make viral proteins.
6 - New viral RNA and proteins move to the cell surface, and a new, immature HIV forms.
7 -Virus is released. Viral protease cleaves new polyproteins to create mature infectious virus.

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17
Q

key enzymes involved in HIV replication

A

protease, reverse transciptase and integrase.

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18
Q

biostere

A

biologically similar shape

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19
Q

NRTI’s - what does it stand for? how do they work?

A

Nucleoside reverse transcriptase inhibitors.
mimic the natural nucleoside that are incorporated into the double helix chain of DNA-RNA and DNA. when incorporated into the growing chain it causes chain termination and so no more HIV can be made and CD4 cells are not further compromised.

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20
Q

what are NRTI drugs activated by

A

viral kinase

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21
Q

in NRTI’s what do base pairs, triphoshate and the N3 in NRTS’s allow for?

A

base pairs- allow for double strands
thriphoshate- allows for chain elongation
N3- essentially makes the NRTI work as it means chain termination.

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22
Q

example of NRTI

A

Zidovidine

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23
Q

NNRTIs what does it stand for how do they work?

A

Non-Nucleoside reverse transcriptase inhibitors. known as allosteric inhibitors and bind to a lipophilic pocket at the base area of the RT enzyme. conformationally prevents the enzyme from allowing the single strand of RNA to be transcribed, protecting replication and protecting CD4 cells

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24
Q

what shape are 1st gen NNRTIs

A

butterfly wing

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25
Q

what shape are 2nd gen NNRTIs

A

horse shoe type shape

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26
Q

example of NNRTIs

A

remdesivir

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27
Q

how is remdesivir different to NRTIs

A

3’ hydroxyl group is present
glycosidic bond c-c is more stable therefore harder to cleave by nucleases
cyano group provides less toxicity and increases stability
more lipophilic
phosphates are highly charged

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28
Q

what are protease inhibitors

A

large proteins made following transcription and translation. processed into smaller proteins to make virion.
protease ‘cleaves’ the larger proteins and hydrolysis pf the protein peptide bond occurs.

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29
Q

what inhibits proteases

A

other small molecules. they will not get cleaved but prevent natural molecules from getting in.

30
Q

the __ the nM, the more potent a drug is

A

lower.

31
Q

an ideal formulation should _

A

no interactions of the excipients
be able to reach the site of action
have rapid onset and controllable duration
be free of undesirable side-effects

32
Q

to be suitable for topical drug delivery, drug should have a __ molecular weight of __, be moderately lipophilic and be effective at low doses of _

A

low, less than 500Da, less than 10mg/day

33
Q

advantage of topical administration to the skin

A

local action

34
Q

what is the principal barrier to drug delivery in topical administration via the skin?

A

stratum corneum

35
Q

advantages of ointments, gels and creams

A

good residence time on skin, good acceptance from the patient

36
Q

ointments what are they? what are the advantages and disadvantages?

A

hydrophobic fatty preparations used on dry lesions such as impetigo
advantage; highly occlusive therefore increase of transdermal drug flux and prolonged drug delivery
disadvantage; messy to use

37
Q

what are gels? advantages and disadvantages?

A

Gels: preparations formed from a liquid phase that have been thickened with other components. Good for treating rosacea.

38
Q

creams - what are they? advantages and disadvantages

A

Creams; most common semi-solid topical formulation, made of 2-phased emulsion w/0 or o/w. Advantages; w/o emulsions less greasy than ointments, easier to apply, can be washed off skin surface. Disadvantage; less occlusive and so less beneficial in dry skin conditions

39
Q

what components increase diffusion in nail lacquers?

A

keratolytic components - increase diffusion through the nail plate

40
Q

eye drop benefits and disadvantages?

A

easy to administer, homogenous therefore better dose uniformity. rapidly drained out of the eye therefore lack of efficacy

41
Q

eye ointments. benefits and disadvantages?

A

Advantages: reduce drug drainage caused by tear flow and so increase corneal residence time. There is sustained drug release of 2-4 h. Disadvantages; more difficult to administer than solutions, more variable administered dose, blurring of vision leading to reduction of patient compliance

42
Q

advantages and disadvantages of pessaries?

A

Advantages; treatment of local infections with a much lower dose than with oral administration. No need of absorption of the drugs for local action. Disadvantage: release of the drugs influenced by varying volumes of vaginal fluids.

43
Q

where does drug absorption take place in the oral route?

A

throughout epithelial and mucosa of the GI tract.

44
Q

advantages of oral route

A

the simplest, most convenient and safest means of drug administration

45
Q

disadvantages of oral route

A

possibility of irregular absorption of certain drugs.

46
Q

are capsules or tablets faster acting?

A

caspules

47
Q

advantages of using capsules in the oral route?

A

use of colour for identification, easy to swallow shape, shell that masks the taste of the fill

48
Q

disadvantages of capsule use

A

Bulky materials can result in large capsule size, susceptible to moisture, not suitable for the administration of drugs which are inactivated in the stomach

49
Q

put in order of drug release fastest to slowest
tablet powder capsule

A

powder capsule tablet

50
Q

disadvantages of powder formulations

A

Not suitable for the administration of drugs which are inactivated in the stomach. Less convenient to carry and to self-administer as liquid preparations than tablets or capsules.

51
Q

are suspensions or syrups faster acting?

A

syrups

52
Q

what do suspensions allow for?

A

slow and prolonged release of the drug - risk of sedimentation though

53
Q

advantages and disadvantages of syrups

A

drugs is already dissolved so quick absorption, masking of unpleasant taste, easy to adjust dose for weight.
risk of deterioration faster than solid dosage forms, inaccuracy in patient measuring dose with spoon

54
Q

how long are injections and infusions administered in

A

injections = less than 15 mins
infusions = more than 15mins in volumes of 100ml - 1000ml

55
Q

depot injection

A

dispersion of the drug in an oily vehicle => slow release of the drug. It is an intramuscular injection deep into skeletal muscles, a viscous formulation of large volume and releases antibiotic load for weeks. 5ml maximum volume.

56
Q

advantages and disadvantages of depot injection

A

Advantages of this are; long lasting effect therefore a limited umber of injections are required. Disadvantages; negative patient acceptance due to pain, unable to discontinue the medication for weeks in the case of adverse effects.

57
Q

liposomes

A

Spherical vesicles in which a lipid bilayer membrane delimitates a central aqueous compartment. Therefore, can carry hydrophilic and lipophilic drugs.
Liposomes form when the phospholipids are exposed to an aqueous environment.

58
Q

is AmBisome or Fungizone more toxic? which is cheaper?

A

Fungizone cheaper but 80 times more toxic

59
Q

is vancomycin used to treat gram negative or positive infetions? why is this? what type of resistance is this a demostration of?

A

gram positive. the structure is too large and of too high molecular weight to go through the porins of gram-negative bacteria therefore is resistant to them. intrinsic resistance.

60
Q

acquired resistance (vertical)

A

the transfer of genetic information from parent to the next generation. Therefor transferring genetic resistance down generation to generation.

61
Q

acquired resistance (horizontal)

A

doesn’t care about one generation to the other.
Can happen between one species to another through 3 methods;
Conjugation; close contact. Bacteria being close together genes can be transferred through pili.
Transduction; transfer through a vector, via viruses
Transformation; occurs through lysis

62
Q

what is used to treat MRSA

A

vancomycin

63
Q

what type of bacteria is the current biggest cause for concern in antimicrobial resistance

A

gram negative

64
Q

how is C diff transmitted? what are the symptoms and possible cause?

A

transmitted by contaminated spores which are then ingested. These ingested spores produce toxins in the lower GI tract which cause colitis. Symptoms vary from mild diarrhoea to severe bloody diarrhoea. The onset of CDI is usually after antibiotic therapy.

65
Q

is C Diff gram positive or negative

A

gram positive

66
Q

what are the 4 C’s which may increase chance of C.diff

A

Clindamycin, cephalosporines, co-amoxiclav and quinolones

67
Q

what is used to treat impetigo

A

ointment

68
Q

what is used to treat rosacea

A

gels - e.g., metronidazole gel

69
Q

side effects of liposomes (fungizone)

A

renal toxicity
cardiovascular toxicity
hematological toxicity

70
Q

in AmBisome the drug is located in;
a) the aqeuous compartment
b) in the bilayer membrane
c)in both the aqueous compartment and the bilayer membrane

A

B) the bilayer membrane

mp321 (5 decks)

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