According to WHO recommendations, the following treatment regimens should be used:

Note that the number before the bracket refers to the number of months the drug is taken.
Category I and III patients are treated in the intensive phase with combinations of four 'first-line' drugs: isoniazid, rifampicin, pyrazinamide and ethambutol for two months, which can be summarised as 2 (HRZE). In the continuation phase, they receive either a combination of isoniazid and rifampicin for four months 4 (HR), or a combination of isoniazid and ethambutol for six months 6 (HE).
For Category I patients with a smear-positive sputum result after two months of intensive treatment, extend the intensive phase for an additional one month. Then follow the continuation phase as above. If a patient is still smear-positive after five months of treatment, then they need to be categorised as 'treatment failure' and restart treatment (Category II).
Category II patients are treated with five drugs for the initial two months of the intensive phase: a combination of isoniazid, rifampicin, pyrazinamide and ethambutol 2 (HRZE), plus streptomycin (S); then continue with four drugs, excluding streptomycin, for an additional one month; then followed by five months of the continuation phase with isoniazid, rifampicin 5 (HR), and ethambutol (E).
Category IV patients are treated with 'second-line' anti-TB drugs, which you do not need to know the details of.

These different treatment regimens are summarised in the following table:

Recommended treatment regimens for each treatment category.

Treatment category	TB treatment regimen
Treatment category	Intensive phase (daily or three times every week)	Continuation phase (daily or three times every week)
I	2 (HRZE)	4 (HR)
II	2 (HRZES) followed by 1 (HRZE)	5 (HRE)
III	2 (HRZE)	4 (HR)
IV	Second-line drugs	Second-line drugs

Knowing this information will enable you to understand the type of drug regimen prescribed by the doctor or clinician for different patient categories. This will help you ensure that the drug treatment is being followed correctly.

The two tables below show the amounts of the different drugs to be administered to patients — in particular the number of tablets they take at any one time. The number of tablets depends upon the body weight of the patient. You are not expected to know the precise dosage of each drug — for example how many milligrams of isoniazid is taken when the patient takes their tablets — but it is very important for you to know the number of tablets a particular patient should be taking. So it is important to check the weight of your patients periodically and refer them to a clinician for an adjustment of drug dose if there is change in their body weight during treatment.

Drug dosage of Category I and III regimens: (2 HRZE) followed by (4 HR).

Regimen	Intensive phase (2 months)	Continuation phase (4 months)
	2 (HRZE) daily	4 (HR) daily
	H 75 mg + R 150 mg + Z 400 mg + E 275 mg tablets	H 150 mg + R 150 mg tablets
Patient's weight	Number of tablets		Number of tablets
20–29 kg	1½	1
30–39 kg	2	1½
40–54 kg	3	2
55–70 kg	4	3
Over 70 kg	5	3

The table above shows the 2 (HRZE) and 4 (HR) drug regimen for categories I and III.

Dosage for Category II regimen: 2 (HRZES), then 1 (HRZE), then 5 (HRE)

Regimen	Intensive phase (3 months)		Continuation phase (5 months)
	2 (HRZES) then 1(HRZE) daily		5 (HRE) (three times per week)
	H 75 mg + R 150 mg + Z 400 mg + E 275 mg tablets	S (vials) 1 g intramuscular	H 75 mg + R 150 mg + E 400 mg tablets
Patient's weight (kg)	Number of tablets	Number of vials	Number of tablets
20–29 kg	1½	½	1½ + 1
30–39 kg	2	½	2 + 1½
40–54 kg	3	¾	3 + 2
55–70 kg	4	1	4 + 3
Over 70 kg	5	1	5 + 3

What is the regimen prescribed for the Category II relapsed TB patient?

Show answer

The drug regimen used for Category II is 2 (HRZES), then 1 (HRZE), then 5 (HRE). Because the intensive phase is three months, but streptomycin is used for only two months (56 doses), it is helpful to write a reminder on the card about when to stop streptomycin.