Tetracyclines

Question 1

How does tetracyclines work ?

Answer 1

inhibits bacterial protein synthesis; binds to ribosomal 30s subunit.
broad-spectrum, bacteriostatic

Question 2

Name all the tetracyclines ?

Answer 2

demeclocycline
doxycycline
lymecycline
minocycline
oxytetracycline
tetracycline
tigecycline

Question 3

What are the side effects of tetracyclines ?

Answer 3

benign intracranial hypertension: stop if headache and visual disturbances occur

Question 4

Minocycline is rarely used, but what are the side effects of this drug ?

Answer 4

causes vertigo, dizziness, irreversible pigmentation, has greater risk of lupus like syndrome

Question 5

Tetracyclines in general should be avoided in renal impairment, however name two tetracyclines that are safe to use ?

Answer 5

doxycycline and minocycline

Question 6

can tetracyclines cause hepatotoxicity ?

Answer 6

Yes: should be used with caution when given with other hepatotoxic drugs

Question 7

Which two tetracyclines can cause photosensitivity and thus patients should be told to avoid exposure to sunlight/sun lamps ?

Answer 7

DD: demeclocyline, doxycycline

Question 8

What should not be taken with tetracyclines as this will lead to decreased absorption ?

Answer 8

Antacids: Al, Ca, Iron, Mg, Zinc salts 2 hours before and after taking.

Question 9

Milk decreases absorption of which three tetracyclines ?

Answer 9

doxycycline
oxytetracycline
tetracycline

Question 10

Name three tetracyclines that can cause oesophageal irritation and how should they be taken ?

Answer 10

DMT: doxycycline (cap), minocycline(cap/tab), tetracycline (tab): SWALLOW WHOLE WITH FLUID WHILE SITTING OR STANDING

Question 11

Doxycycline should be used with caution in which patient groups ?

Answer 11

• hepatic impairment
• myasthenia gravis: tetracyclines may increase muscle weakness
• systemic lupus SLE: tetracyclines may exacerbate it
• alcohol dependency

Question 12

What are possible adverse effects of doxycycline ?

Answer 12

• Dyspnoea, hypotension, peripheral oedema, tachycardia (common).
• Gastrointestinal disturbances, such as nausea, vomiting, and diarrhoea (uncommon)
• skin hyperpigmentation ( with long-term use )
• Antibiotic-associated colitis, anxiety, arthralgia, flushing, increased intracranial pressure with papilloedema, myalgia, tinnitus, vision disorders (rare)

Question 13

Which antibiotic class can cause severe headache and/or visual disturbance that may suggest benign intracranial hypertension ?

Answer 13

tetracyclines

Question 14

Why the concurrent use of tetracyclines and retinoids should be avoided ?

Answer 14

there is a possible increased risk of benign intracranial pressure if tetracyclines are used concurrently with retinoids (such as isotretinoin).

Question 15

Patient regular medication is carbamazepine and lithium, GP asks if its ok to prescribe doxycycline ?

Answer 15

Better alternative antibiotic as long term use of carbamazepine reduce doxycycline levels significantly and doxycycline can increase the risk of lithium toxicity

Question 16

Which tetracycline is less affected by milk, oxytetracycline or doxycycline ?

Answer 16

doxycycline

Question 17

How should oxytetracycline be taken with food or not ?

Answer 17

on empty stomach, this means an hour before food or 2 hours after food

Question 18

Patient takes warfarin on regular basis and doctor would like to prescribe tetracycline and asks for your advice /

Answer 18

the concurrent use of warfarin with tetracyclines can increase the anticoagulant effect of coumarins.
Monitor the person’s international normalized ratio (INR) regularly and within 3 days of starting the tetracycline. Adjust the warfarin dose accordingly.

Question 19

Patient has renal impairment and doctor asks you if doxycycline or oxytetracycline better ?

Answer 19

doxycycline