AusDoc 20th Mar | Page 30

Rifampicin( four months)

Orange discolouration of urine, tears, saliva, semen, contact lenses Hepatotoxicity Rash / hypersensitivity Gastrointestinal upset Thrombocytopenia Haemolytic anaemia

Strong inducer of CYP450 liver enzyme system Reduces levels of many drugs— importantly, calcineurin inhibitors, tofacitinib, corticosteroids, opioids, azole antifungals, oral oestrogens May compound effects of others

Liver enzyme induction lasts approximately four weeks

Figure 5. Methods used to diagnose latent TB infection.

Therefore, initiation of preventive

treatment does not constitute a medical emergency. For example, a positive IGRA in an immunosuppressed patient, or one in whom immunosuppression is planned, who does not have any features of active TB is not an indication for

preventive LTBI treatment can interact with many drugs. Advise patients to ensure the doctor has checked if there are any interactions before starting them on any new drugs.

Importantly, rifampicin can reduce the efficacy of oestro-

CC BY / Yale Rosen: bit. ly / 3I7AO64

referral to ED. Refer these patients

gen-based oral contraceptive pills,

to an infectious diseases specialist.

so for women of childbearing age

Starting preventive treatment

on oestrogen-based contraception,

depends upon whether the immu-

recommend the use of additional

nosuppression is already in place

barrier methods.

and, if not, the urgency of initiating or escalating the immunosuppression. For example, a patient with a

Adherence

Adherence to LTBI preventive treat-

new diagnosis of acute leukaemia will need to start chemotherapy as soon as possible; however, a patient with rheumatoid arthritis may be

ment is important to achieve the desired outcome of reduction in the risk of TB reactivation. For example, 12 months of isoniazid therapy

Figure 6. CT scan showing cavitary TB.

able to delay starting a biologic agent for some weeks.

Once active TB has been

was associated with a 60 % protective effect for TB; however, in patients with good compliance, the

as well as recommendations for tools— such as a pill organiser

Surveillance for active TB

Whether a patient with LTBI

educate them about the signs and symptoms of active TB.

excluded, the patient has demonstrated they are tolerating the

efficacy increased to 93 %. 46-48 Patient education about adherence

box or phone reminders— may be prudent.

receives or does not receive preventive treatment, it is important to

Discuss the symptoms of active

TB, including fever, night sweats,

preventive treatment and drug

interactions are not an issue, the author recommends contacting the referring specialist to let them know they are able to start or increase the immunosuppression. The author’ s approach to the initiation of LTBI preventive treatment in relation to immunosuppression appears in figure 8.

Figure created in BioRENDER. com

SURVEILLANCE AND FOLLOW-UP

FIGURE 9 summarises the key

areas for patient education when

LTBI preventive treatment is

started.

Side effects

Monitor for adverse effects. Perform

LFTs, FBC and EUC. In

patients receiving LTBI preventive

treatment, the author recommends

blood testing at two weeks and

then regularly( monthly or every

second month) throughout the

treatment.

Educate the patient regarding

hepatotoxicity and the symptoms

of liver injury— such as nausea,

abdominal pain, jaundice, fatigue

— and that, if these occur, they

should stop the preventive medications

and seek medical attention.

Advise patients to avoid alcohol.