SHORT COMMUNICATION Over-the-counter sales of drugs used as second-line therapy for tuberculosis in different parts of the world: a review Bella Devaleenal Daniel 1 • Prathiksha Giridharan 1 • Mohan Natrajan 1 Ó Springer International Publishing AG, part of Springer Nature 2018 Abstract The increasing burden of drug-resistant tuber- culosis (TB) is a major public health concern, and effective strategies need to be planned to prevent its emergence and transmission. Private healthcare centres and pharmacies are the first point of healthcare access in many low- and middle-income countries. The prevalence of resistance to second-line anti-TB drugs, especially fluoroquinolones, is high in some countries with a high TB burden. In these countries, second-line anti-TB drugs, such as fluoro- quinolones, amoxicillin–clavulanate and injectable agents such as amikacin, are often available as over-the-counter drugs, often taken as self-medication and used for other indications. Stringent policies and effective implementa- tion need to be in place for preventing the inappropriate use of these drugs to prevent the emergence of drug resistance. Background Tuberculosis (TB) has been a major public health concern since ancient times. Globally, there were an estimated 10.4 million new cases of TB, 490,000 new cases of multidrug- resistant TB (MDR-TB) and an additional 100,000 people with rifampicin-resistant TB (RR-TB) in 2016 [1]. With the implementation and distribution of anti-TB therapy (ATT) through national programmes, many countries have been able to control TB to a major extent. However, the increasing burden of drug-resistant TB (DR-TB) is a major public health concern and an obstacle for the effective control of TB. In 2016, 47% of MDR/RR-TB cases were reported from China, India and the Russian Federation [1]. The 2011 World Health Organization (WHO) update recommended that the MDR-TB regimen should include at least pyrazinamide, a fluoroquinolone, a parenteral agent (amikacin, capreomycin or kanamycin), ethionamide or prothionamide, and either cycloserine or para-aminosali- cylic acid (PAS) if cycloserine cannot be used [2]. The decision on each country’s standard regimen for MDR-TB should be based on drug-resistance surveys, estimates of MDR levels and other data sources [3]. Prior exposure to second-line drugs among patients on an MDR-TB regimen is a risk factor for development of extensively drug-resis- tant TB (XDR-TB) [4]. The current 2016 WHO update recommends that, in patients with RR- or MDR-TB not previously treated with second-line drugs and in whom resistance to fluoro- quinolones and second-line injectable agents has been excluded or is highly unlikely, a shorter regimen of 9–12 months may be used [5]. The following are the latest groups of drugs indicated to treat DR-TB: • Group A levofloxacin, moxifloxacin, gatifloxacin • Group B amikacin, capreomycin, kanamycin, streptomycin • Group C ethionamide (or prothionamide), cycloserine (or terizidone), linezolid, clofazimine • Group D1 pyrazinamide, ethambutol, high-dose isoniazid • Group D2 bedaquiline, delamanid • Group D3 PAS, imipenem-cilastatin, meropenem, amoxicillin–clavulanate, thioacetazone [5]. & Mohan Natrajan mohan.n@nirt.res.in 1 Department of Clinical Research, National Institute for Research in Tuberculosis (ICMR), No. 1, Mayor Sathyamoorthy Road, Chetpet, Chennai, Tamil Nadu 600031, India Drugs Ther Perspect https://doi.org/10.1007/s40267-018-0510-6