2. Tetracyclines

Question 1

Tetracycline spectrum of activity

Answer 1

broad-spectrum

Question 2

Tetracycline mechanism of action

Answer 2

Prevents protein synthesis which prevents bacteria from growing , by binding to the 30S subunit of ribosome (bacteriostatic).

Question 3

Examples of tetracylines

Answer 3

Doxycycline, Minocycline, Lymecycline

Question 4

Minocycline side effects

Answer 4

Dizziness, vertigo, lupus-erythematous

Question 5

Tetracyclines primarily treat

Answer 5

chlamydia, malaria prophylaxis, respiratory tract infections, acne and rosacea

Question 6

Typical doxycycline dose

Answer 6

200mg OD

Question 7

Tetracyclines side effect

Answer 7

Benign intracranial hypertension (symptoms: headache, visual disturbances). Must STOP the drug if this happens

Tooth discolouration and dental hyperplasia, as they bring to calcium in growing bone and teeth.

Photoxicity, sunburns when exposed to sunlight, which is common with Democlocyline and Doxycline. Counselling/label would be avoid sunlight or lamps, protect skin from sunlight even on a cloudy day. Do not use sunbeds.

Question 8

Apropriateness of tetracyclines in pregnancy

Answer 8

tetracyclines are unsuitable in pregnancy

Question 9

Tetracyclines contraindications

Answer 9

Patients below the age of 12, as they permanently discolour teeth. Except Doxycycline and Lymecycline, contraindicated in under 8 years and 8-11 years respectively.

Tetracyclines should be AVOIDED in renal impairment except doxycycline and minocycline

Tetracyclines should be avoided in hepatic impairment

Question 10

Tetracyclines interaction

Answer 10

As tetracycline are hepatotoxic drugs, the hepatotoxicity is further increased with another hepatotoxic drug. Examples include antibiotics (co-amoxicalv, flucloxacillin), anti-epileptics (carbamazepine and valproate), fluconazole, intraconazole, methotrexate, sulfasalzine.

Question 11

tetracycline counselling labels

Answer 11

For all tetracyclines: antacids, iron or zinc should be avoided 2 hours before taking them

ADDITIONALLY

For Demeclocycline, oxytetracycline:
Milk should be avoided 2 hours before taking the medicine. It should also be taken on an empty stomach (an hour before food or 2hrs after food).

Doxycycline irritate the lining of the oesophagus, leading to ulcers and dysphagia.

DM have administration requirements (Doxycycline, Minocycline). Should be swallowed whole with plenty of water sitting or standing.