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Treatment strategy & Regimens used in Egypt. Different treatment strategies available. Standardized treatment. Designing this treatment regimen depends on representative DRS data. All patients in a patient group or category receive the same regimen.
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Standardized treatment. • Designing this treatment regimen depends on representative DRS data. • All patients in a patient group or category receive the same regimen. • Standardized treatment followed by individualized treatment • Initially, all patients in a certain group receive the same regimen based on DST survey data from representative populations. • The regimen is adjusted when DST results become available. • Empirical treatment followed by individualized treatment • Each regimen is individually designed on the basis of patient history. • Then adjusted when DST results become available.
Advantages of standardized regimens: • based on representative DRS. • enable more patients to access care • maintaining cure rates comparable to those obtained with individualized treatment • simpler operational aspects of implementation, • simpler drug ordering, • easier training, • less likelihood of mismanagement, • Less dependence on highly technical laboratories.
Individualized treatment strategies • Requires laboratory capacity to perform DST of second-line drugs. Advantages of individualized regimens • Avoid placing patients on toxic and expensive drugs to which the strain is resistant. • Preferred in settings with high rates of resistance to second-line drugs
The most frequently used strategy in settings where second-line drugs have not been widely used e.g. Egypt, is a combination of standardized and individualized treatment. • For example, DST of H, R, E and S are checked only and place any patients with documented resistance on different standardized regimens based on the pattern of resistance found.
Based on the history of drugs taken by the patient & Drugs and regimens commonly used in the country. • prevalence of resistance to first-line and second-line drugs should be taken into consideration • Regimens should consist of at least four drugs with either certain, or almost certain, effectiveness. • Often, more than four drugs may be started if the susceptibility pattern is unknown, • Drugs are administered at least six days a week. • When possible, pyrazinamide, ethambutol and fluoroquinolones should be given once per day because the high serum levels attained in once-a-day dosing may be more efficacious.
Once-a-day dosing is permitted for other second-line drugs, depending on patient tolerance. • The drug dosage should be determined by body weight. • An injectable agent (an aminoglycoside or capreomycin) is used for a minimum of 6 months • Treatment is for a minimum duration of 18 months beyond sputum conversion. • Each dose is given as DOT throughout the treatment. • DST, when available and from a reliable laboratory, should be used to guide therapy. • Pyrazinamide can be used for the entire treatment if it is judged to be effective. (Many DR-TB patients have chronically inflamed lungs, which theoretically produce the acidic environment in which pyrazinamide is active)
Class 1 – First-line oral anti-tuberculosis • First-line oral anti-tuberculosis drugs should be used where there is laboratory evidence or clinical history to suggest their efficacy. • Patient who is resistance to low levels of Isoniazid but are susceptible to higher concentrations may benefit from high dose of the drug but should not be included as one of the four core drugs.
Class 2 – injectable agents • A Group 2 injectable agent should be given to all patients in whom susceptibility is documented. • streptomycin is the usual injectable agent of choice • Kanamycin or amikacin is the logical second choice given the low cost of these drugs and good experience of their use. • If an isolate is resistant to both streptomycin and kanamycin, capreomycin should be used. • Duration of injectable agent (intensive phase) is guided by smear and culture conversion. • At least 6 months and at least 4 months after the patient first becomes and remains sputum smear- or culture-negative.
Intermittent therapy (3-5 times weekly after an initial period of 2–3 months of daily therapy) can be considered for patients in whom the injectable agent has been used for a prolonged period and when the risk of toxicity increases.
Class 3 – Fluoroquinolones • Should be used whenever the strain is susceptible. • The most potent according to in vitro studies in descending orders are:- • Moxifloxacin = Gatifloxacin • Levofloxacin • Ofloxacin = Ciprofloxacin • Long-term safety of the newer-generation Fluoroquinolones has not yet been fully evaluated.
Class 4 – Oral bacteriostatic second-line anti-tuberculosis drugs • If only one is needed, ethionamide/protionamide is often added because of its proven efficacy and low cost. • If cost is not a constraint, PAS may be added first because the enteric- coated formulas are relatively well tolerated. • If two agents are needed, Cycloserine is commonly used in conjunction with ethionamide/protionamide or PAS. • Combination of ethionamide/protionamide and PAS has a high incidence of gastrointestinal adverse effects,
Class 4 – Oral bacteriostatic second-line anti-tuberculosis drugs, (cont.) • Ethionamide/protionamide should be started at a low dose (250 mg) for a few days and then gradually increased every 3–5 days. • The use of thioacetazone is limited by the development of rashes that are more prevalent in HIV-positive individuals and can result in Stevens-Johnson syndrome and death. • In addition, thioacetazone has cross-resistance with the thioamides (ethionamide and protionamide) and is considered a relatively weak antituberculosis agent.
Class 5. • Not recommended by WHO for routine use in DR-TB treatment because their contribution to the efficacy of multi-drug regimens is unclear. • can be used in cases where adequate regimens are impossible to form with the medicines from Groups 1–4.
Duration of treatment • Treatment should last for at least 18 months after culture conversion. • Extension to 24 months may be indicated in patients with extensive pulmonary damage
Extra-pulmonary DR-TB and DR-TB treatment: • Treatment strategy is the same • When CNS is involved, Rifampicin, isoniazid, pyrazinamide, protionamide/ethionamide and cycloserine have good penetration into CNS. • kanamycin, amikacin and capreomycin penetrate effectively only in the presence of meningeal inflammation; PAS and ethambutol have poor or no penetration.
Suggested treatment regimens for mono &poly-resistance patterns
