tetracyclines

Question 1

cautions for all tetracyclines (2)

Answer 1

myasthenia gravis - muscle weakness may be increased
- SLE may be exacerbated

Question 2

common side effects

Answer 2

• angiodema
• hypersensivitiy
• diarrhhoea
• headache
• nausea
• pericarditis
• photosensitivity reaction
• skin reactions
• SLE exacerbated
• vomiting
• headache and visual disturbances (may indicate benign intracranial hypertension - discontinue if raised IC pressure develops!)

Question 3

what is Henoch-Schonlein purpora?

Answer 3

inflammation of small blood vessels which leak into skin, joints, intestines and kidneys
appears as purpuric rash

Question 4

Answer 4

Henoch Schonlein purpura
common side effect of tetracyclines

Question 5

headache and visual disturbances as a side effect of tetracyclines can indicate…

Answer 5

benign intracranial hypertension
discontinue if raised intracranial pressure

Question 6

can you use in pregnancy and why

Answer 6

• no
• 1st trimester: animal studies show effects of skeletal development
• 2nd trimester: can cause discolouration of child teeth
• maternal hepatotoxicity with large parenteral doses

Question 7

can you use in BF and why

Answer 7

Do not give, although absorption and therefore discoloration of teeth in infant is probably usually prevented by chelation with calcium in milk

Question 8

DLM

Answer 8

do like milk - doxy, Lyme, minocycline

Question 9

DOT

Answer 9

don’t like milk - demeclo, oxytetra, tetracycline

Question 10

photosensitivity reactions are more likely with this abx than other tetracyclines

Answer 10

demeclocycline

Question 11

tetracyclines are …. toxic

Answer 11

hepatotoxic

Question 12

which abx is used for treatment of hyponatraemia resulting from inappropriate secretion of ADH if fluid restriction alone does not restore sodium conc or is not tolerable?

Answer 12

demeclocycline

Question 13

doxycycline is normally contraindicated in pregnancy because of risk of skeletal development impaired and staining of teeth in baby. however, if travel to malarias areas is unavoidable and other regimens are unsuitable, it can be used for malaria prophylaxis if the entire course can be completed before…..

Answer 13

15 weeks gestation

Question 14

labelling requirements for doxycycline (in addition to standard abx ones)

Answer 14

• do not take indigestion remedies …
• protect skin from sunlight ….
• take with full glass of water….

Question 15

which abx has an additional warning label of ‘take with full glass of water’?

Answer 15

doxycycline

Question 16

which abx is associated with a greater risk of lupus-erythematous like syndrome compared to other tetracyclines?

Answer 16

minocycline

Question 17

which abx sometimes causes irreversible pigmentation?

Answer 17

minocycline

Question 18

tetracyclines are contraindicated in this age … because…

Answer 18

• <12
• deposition in growing bone and teeth, by binding to calcium, causes staining and occasionally dental hypoplasia

Question 19

dairy products decrease the exposure to these two abx

Answer 19

demeclo, oxytetra

Question 20

interactions - retinoids

Answer 20

increased risk of being intracranial hypertension. avoid

Question 21

interactions - warfarin, acenocoumarol, pheninidoine

Answer 21

increases AC effect - monitor INR

Question 22

interactions - which drugs increase risk of hepatotoxicity

Answer 22

• azoles
• vitamin A
• valproate
• thalidomide
• testosterone
• statins
• paracetamol
• MTX
• mercaptopurine
• heparin
• isoniazid
• fluorouracil
• amiodarone

Question 23

does MTX interact?

Answer 23

increased risk of hepatotoxicity

Question 24

does lithium interact?

Answer 24

abx predicted to INCREASE risk of lithium toxicity
avoid or adjust dose

Question 25

can you take iron and tetracyclines at the same time

Answer 25

Decreases absorption of oral abx
Take abx 2-3 hours after iron

Question 26

can you take calcium at the same time as tetracyclines

Answer 26

oral calcium predicted to decrease absorption of abx.
separate by 2-3 hours

Question 27

can you take oral bismuth and antacids at the same time as tetracyclines

Answer 27

separate by 2-3 hours
greatly decreases efficacy of oral abx

Question 28

can you take zinc at the same time as tetracyclines

Answer 28

decreases absorption of abx separate administration by 2-3 hours

Question 29

dose of doxycycline in CAP, acute cough, acute sinusitis

Answer 29

200mg stat, then 100mg once daily. total 5 days. total you would prescribe = 6 tablets

Question 30

dose of doxycycline for HAP

Answer 30

200mg stat, then 100mg once daily. total 5 days, then review

Question 31

dose of doxycycline for acute exacerbation of bronchiectasis

Answer 31

200mg stat, then 100mg once daily for 7-14 days total

Question 32

dose of doxycycline for acute exacerbation of COPD

Answer 32

200mg stat then 100mg OD for 5 days total
increased if necessary to 200mg OD (severe infections)

Question 33

dose of doxycycline for PID

Answer 33

100mg BD for 14 days

Question 34

oxytetracycline labels (in addition to space doses evenly, take course until finished) - 2

Answer 34

DOT - do not take milk, indigestion remedies, or meds containing iron or zinc 2 hr before or after
take on empty stomach - an hour before food or 2 h after food