Tetracyclines

Question 1

list 4 tetracyclines

Answer 1

1) Doxycycline
2) Tetracycline
3) Lymecycline
4) Minocycline

Question 2

what is the spectrum of activity of tetracyclines?

Answer 2

1) Broad spectrum of activity

2) Gram-positive and Gram-negative organisms, including chlamydia, mycoplasma and spirochaetes

Question 3

outline the MoA of tetracyclines

Answer 3

1) Bacteriostatic
2) Tetracyclines inhibit bacterial protein synthesis. They bind to the ribosomal 30S subunit found specifically in bacteria

Question 4

what are tetracyclines commonly indicated for?

Answer 4

1) Chlamydia
2) Acne, rosacea, rickettsia
3) typhoid, anthrax, malaria and Lyme disease (Borrelia burgdorferi
4) LRTI e.g. infective exacerbations of COPD (e.g. Haemophilus influenzae), pneumonia

Question 5

List the important side effects caused by tetracyclines

Answer 5

1) Tetracycline-specific side effects include: oesophageal irritation, ulceration and dysphagia- drink plenty of water
2) Photosensitivity
3) Discolouration of tooth enamel in children
4) intracranial hypertension which causes headache and visual disturbance
5) Blood disorders, and hepatotoxicity
6) Colitis

Question 6

who should tetracyclines be used in caution with?

Answer 6

1) Binds to teeth and bones during fetal development and in children. Avoid in <12 years, BF and pregnancy
2) caution AVOID in renal and hepatic impairment
3) Myasthenia gravis, systemic lupus erythematosus

Question 7

What are the important interactions with regards to tetracyclines?

Answer 7

1) Salts can decrease absorption - do not take within 2 hours of indigestion remedies, calcium or iron
2) Milk may reduce absorption
3) effects of warfarin may be increased

Question 8

what patient and carer advice needs to be provided to those taking tetracyclines?

Answer 8

1) Tablets should be swallowed whole with plenty of fluid while sitting or standing
2) indigestion remedies and milk
3) Headache and visual disturbances may indicate benign intracranial hypertension (discontinue treatment if raised intracranial pressure develops)
4) Patients should be advised to avoid exposure to sunlight or sun lamps
( tetracycline the drug itself- empty stomach)

Question 9

when can doxycycline be used in pregnancy?

Answer 9

1) When travel to malarious areas is unavoidable during pregnancy
2) for malaria prophylaxis if other regimens are unsuitable, and if the entire course of doxycycline can be completed before 15 weeks’ gestation

Question 10

demeclocycline is known for causing what electrolyte imbalance?

Answer 10

1) increases sodium concentrations in patients with syndrome of inappropriate antidiuretic hormone
2) also greater risk of erythematous-like syndrome

Question 11

how long is lymecycline prescribed for the treatment of acne?

Answer 11

408mg for at least 8 weeks - commonly causes GI discomfort