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PHAR20400 > Semester 1 Public Drugs > Flashcards

Semester 1 Public Drugs Flashcards

1
Q

SALVARSAN

A
  • First chemotherapy drug to treat Syphilis.
  • Discovered by Paul Ehrlich whilst looking for a cure for sleeping sickness.
  • Mixture of a trimer and pentamer structures that contain ARSENIC.
  • High arsenic content made the drug highly toxic.
  • A PRODRUG which is oxidised to oxophenarsine.
  • Oxophenarsine reacts with thiol grops in proteins - targets bacteria due to the fact they replicate their cells quicker than humans.
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2
Q

NEOSALVARSAN

A
  • A sulphur group added to salvarsan in order to make the drug more soluble and therefore less toxic.
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3
Q

TETRACYLCINES

A
  • Integrated - Doxycycline for Malaria Prophylaxis
  • Integrated - Minocycline for Neisseria meningtidis
    These bind directly to the ribosome to inhibit protein synthesis. Binding so that elongation factor TU is unable to bring the next amino acid to the ribosome.
    These are both semi-synthetic tetracyclines.

ContraIndicated in children because it stains tooth enamel.

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4
Q

Resistance to Tetracyclines

A

is membrane associate, but mutations in the S10 can also give rise to resistance

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5
Q

AMINOGLYCOSIDES

  • Gentamicin
  • Streptomycin
  • TOBRAMYCIN
A

Very hydrophilic so are given IV because they cannot cross the gut wall.

Narrow Therapeutic Index - Nephrotoxicity

Work by binding to the 30S ribosomal subunit. Binding so that the A site is inhibited and the genetic code is misread.

Good for gram negative - which is usually more difficult to treat.

Tobramycin - for the treatment of Pseudomonas aeruginosa infections. Inhaled.
This aminoglycoside also binds to the 50S as well as the 30S, preventing them from combining.

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6
Q

LINEZOLID (oxazolidinone)

A

Inhibits the INITIATION stage, and prevents the 50S and the 30S subunit from binding together.

Active against MRSA - drug is kept back to fight hospital acquired infections.

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7
Q

MACROLIDES
- erythromycin

2nd Gen

  • Azithromycin
  • Clarithromycin
A

blocks the 50S subunit
gram positive bacteria

azithromycin & clarithromycin are much more hydrophobic and therefore ore stable in the stomach than erythromycin

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8
Q

Side Effects of Macrolides

A

Generally, not very well tolerated

  • Gut Motile Agonists (sickness/diarrhoea) - can give azithromycin instead
  • Taste not masked easily - esterify the drug to make a prodrug, so that it is taste free and can be hydrolysed in the blood. THIS MEANS THAT THE MEDICINE WILL THEN HAVE TO STAY IN THE FRIDGE OR IT MAY BE HYDROLYSED IN THE BOTTLE. Erythromycin hydrolyses within 10 mins.
  • Metabolised by Cytochrome P450 3A4
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9
Q

CHLORAMPHENICOL

A

Gram Positive or Negative

Formulated as EYE DROPS

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10
Q

CLINDAMYCIN/LINCOMYCIN

A

bind to the same place as macrolides - 50S subunit

Clindamycin is used for

  • ANAEROBIC INFECTIONS of soft tissue
  • AEROBIC INFECTIONS of the resp tract

TOXIC SHOCK SYNDROME - alongside vancomycin
PROTOZOAL INFECTIONS - alongside chloroquinine/quinine

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11
Q

FUSIDIC ACID

A

Gram Negative Infections
Given as eye drops - or a gel for conjunctivitis

Binds to elongation factor G to stall protein synthesis

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12
Q

B Lactam Ring Containing Antibiotics include:

A

Penicillins
Cephalosporins
Carbapenems

They work by targeting the transpeptidase and the carboxypeptidase enzymes

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13
Q

Penicillin G

A

Only to be administered IV because it is acid labile

Sensitive to B Lactamases produced by bacteria

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14
Q

Ampicillin (Penicillin)

A

Semisynthetic
Able to take orally, not as acid labile
Sensitive to B Lactamases produced by bacteria

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15
Q

Amoxicillin (Penicillin)

A

Semisynthetic
Resistant to Class 1 of B Lactamases produced by bacteria
Taste Masked - good for children

  • Chlamydia trachomitis
  • Non gonococcal urethritis
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16
Q

Methicillin/Flucloxacillin (Penicillin)

A

Resistant to all B Lactamses produced by bacteria

Not readily taste masked

17
Q

Cephalosporins

A

1st Gen - BARELY USED

2nd Gen - gram negative activity, problems with resistance showing

3rd Gen - good gram negative activity, good for serious illnesses and can be injected (Ceftriaxone)

18
Q

Carbapenems

A

Broad Spec Antibiotics and resistant to MOST B Lactamses produced by bacteria

Its the reserve antibiotic

19
Q

VANCOMYICN

A

Works by pushing apart the peptidoglycan chains so that they cannot be cross-linked.

Serious Gram Positive Infections - but doesn’t cross the gut wall.

MSRA
Clostridium difficile

Teicoplanin works in a similar way to vancomycin

20
Q

SULFONILAMIDES

A

Gram positive cocci (pneumococci/meningococci)

21
Q

TRIMETHOPRIM

A

Resembles a part of the pteridine structure (what bacteria make the tetrahydrofolate from)

Blocks the bacterial dihydrofolate reductase - has higher affinity for it than the human one

Used for UTIs
Can be used in combination with other sufonilamides (co-trimoxazole - sulphamethoxazole)

22
Q

Pyrimethamine

A
  • a dihydrofolate reductase inhibitor

- is an antimalarial - chlorophenyl ring makes it too hydrophobic to be able to cross bacterial walls

23
Q

Methotrexate

A
  • a dihydrofolate reductase inhibitor in HUMANS, inactive against bacteria because they don’t have AA transporters
  • glutamate on the group enables it to be actively transported by amino acid transporters
  • similar in structure to folic acid means that it will also be taken up into cells
  • Anticancer Agent
  • Rheumatoid Arthritis
  • IBD - an immunomodulator (also be supplemented with folic acid). Given instead of Azathioprine for maintenance treatment in CD . Given as an IM injection.
  • Terminate pregnancy

Drug Interaction - interacts with Penicillin, penicillin blocks methotrexate’s elimination

24
Q

QUINOLONES

A

MOA: blocks subunit A of DNA Gyrase that usually supercoils DNA into bacterial cells

1st Gen - 3rd Gen, starts off just gram negative but then activity against gram positive improves

2nd Generation Quinolones - Fluoroquinolones, including Ciprofloxaicin

  • for respiratory tract infections BUT NOT pneumococcal pneumonia
  • interactions - CYP450 1A2

3rd Generation Quionolones - Levofloxacin

  • Broad Spectrum
  • Active against Strep (gram positive)
25
Q

DNA Strand Breakers

A

MOA: highly reactive molecules that attack DNA strand breakers and produce radicals that cause cleavage of the sugar phosphate backbone of DNA.

Nitrofurantoin

  • Narrow Spectrum
  • UTIs

Metronidazole

  • Can’t drink alcohol
  • H pylori
  • C difficile (400mg TDS for 7 - 10 days)
26
Q

Antivirals for Influenza

A

Zanamivir / Oseltamivir

  • Transition state inhibitors that target the neuraminidase proteins on the virus
  • Targeting Neuraminidase - only slowing the progression of the disease whilst trying to find some antibodies for the Haemagluttinin proteins
27
Q

Treatment for Chlamydia Trachomitis

A
  • Azithromycin 1g as a single dose
  • Doxycycline 100mg BD for 7 days
  • Erythromycin 500mg BD for 14 days
28
Q

Treatment for Gonococcal Urethritis

A
  • Ceftriaxone IM and Azithromycin PO
  • Cefixime PO and Azithromycin PO

(Cephalosporin and Macrolide)

29
Q

Treatment for Non Gonococcal Urethritis

A
  • Treat as for Chalmydia
  • Azithromycin 1g as a single dose
  • Doxycycline 100mg BD for 7 days
  • Erythromycin 500mg BD for 14 days
30
Q

Treatment for Bacterial Vaginosis

A

Overgrowth of anaerobic organisms rather than the lactobacilli that usually maintains the pH of the vagina

Metronidazole BD for 7 days (DNA Strand Breaker)
Clindamycin BD for 7 days

31
Q

Treatment for Trichmoniasis

A

a PROTOZOAL infection

Metronidazole 2g as a single dose
Metronidazole 400mg BD for 7 days

32
Q

Aciclovir

A

for the treatment of genital herpes

MOA: replaces the normal substrate for DNA synthesis

  • purine analogue
  • inhibits DNA polymerase
  • higher affinity for viral kinases rather than cellular kinases
Side Effects:
Nausea
Diarrhoea
Headache
Tremor 
Delirium
33
Q

Treatment for Syphillis

A

Penicillin G

Doxycycline 100mg BD for 14 days

34
Q

Amphotericin B

A

a POLEYNE anti-fungal

  • binds to ergosterol in the cell membrane of fungi
  • forms pores
  • Oral Infections
  • IV systemic Infections
  • Toxic to the kidneys
35
Q

Nystatin

A

a POLEYEN anti-fungal
- binds to ergosterol in the cell membrane

  • Candida albicans infections of the skin
36
Q

Azole Fungals

A

Fluconazole

Inhibits the CYP450 14alphademethylase enzyme, which stops the conversion of squalene to ergosterol

  • Good oral absorption
  • Cryptococcal meningitis
  • Severe oral/oesophageal candidiasis

PHAR20400 (20 decks)

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