Acne

Question 1

what class of antibiotics are predominantly used to treat acne

Answer 1

tetracyclines

Question 2

indications for tetracyclines

Answer 2

1. acne vulgaris - especially in inflamed papules, pustules, cysts
2. LRTI including infective exacerbations of COPD e.g. HIB, pneumonia, and atypical pneumonia
3. chlamydial infection including PID
4. Othere infections e.g. typhoid, anthrax, malaria, lyme disease

Question 3

what is the spectrum of activity in tetracyclines?

Answer 3

broad spectrum but increased resistance. gram -ve and +ve

Question 4

MOA tetracyline

Answer 4

bind to 30S ribosome so RNA and mRNA cannot bind. It is bacteriostatic.

Question 5

how are bacteria becoming resistant to tetracyclines

Answer 5

• efflux pump allowing bacteria to pump out hte abx

Question 6

SE of tetracyclines

Answer 6

N, V and D- lower risk of CD than penicillins

hypersensitivity reactions

oesophageal irritation, ulceration and dysphagia, photosensitivity, discolouration and/or hypoplasia of tooth enamel in kids

rare - hepatotocivity and ICH - headache and visual changes

Question 7

when should you not prescribe tetracyclines

Answer 7

pregnancy
breast feeding
kids under 12

Question 8

why should you not prescribe tetracycline in pregnancy and kids

Answer 8

bind to teeth and bones

Question 9

who should you reduce the dose of tetracycline for

Answer 9

renal impairment - it has antianabolic side effect - raising urea and reducing excretion

Question 10

interactions of tetracyclines

Answer 10

they bind to divalent cations so not within 2 hrs of calcium, iron or antacids. these will stop absopriton of abx.

also this abx enhances warfarin effect as kills vitamin k fighting bacteria

Question 11

name common tetracyclines

Answer 11

doxycycline

lymecycline

Question 12

how long do u treat acne with tetracyclines for

Answer 12

8 weeks

Question 13

how long do you treat infections with tetracyclines for

Answer 13

5-7 days

Question 14

when should patients be advised to take tetracyclines

Answer 14

with a full glass of water when sitting or standing. they are to avoid indigestion remedies and medicines containing iron or zinc 2hrs before and after taking the antibiotic .

must protect skin from sunlight

Question 15

what side effect is specific to demeclocycline the tetracycline

Answer 15

In SIADH patients it increases sodium concentrations in serum