Tetracyclines

Question 1

Tetracyclines - examples

Answer 1

Doxycycline

lymecycline

Question 2

Tetracyclines - indications

Answer 2

1) Acne vulgaris, particularly where there are inflamed papules, pustules and/or cysts
2) Lower respiratory tract infections
3) Chlamydial infection, including pelvic inflammatory disease.

Question 3

Tetracyclines - MOA

Answer 3

Tetracyclines inhibit bacterial protein synthesis - how?

1) prevents binding of tRNA to mRNA = prevents addition of new amino acids to growing polypeptide chains
2) Inhibition of protein synthesis is bacteriostatic (stops bacterial growth)
3) this allows the immune system to kill and remove the bacteria from the body

Question 4

Tetracyclines - Adverse effects

Answer 4

1) nausea +/- vomiting
2) diarrhoea
3) Hypersensitivity reactions occur in about 1%, including immediate and delayed reactions
4) oesophageal irritation, ulceration and dysphagia
5) photosensitivity (an exaggerated sunburn reaction when skin is exposed to light)
6) discolouration +/- hypoplasia of tooth enamel in children
7) Rare, but serious - hepatotoxicity and intracranial hypertension, the latter causing headache and visual disturbance.

Question 5

Tetracyclines - Used with caution in pxts with…

Answer 5

renal impairment

Question 6

Tetracyclines - avoided in patients with…

Answer 6

pregnancy

breastfeeding

children ≤12 years of age

Question 7

Tetracyclines - interactions

Answer 7

Warfarin

Should NOT be given within 2 hours of:
1) calcium
2) antacids
3) iron
Why? Will prevent antibiotic absorption