[Relationship between the weight of hospitalized patients with pulmonary tuberculosis and the oral dose of isoniazid].

Objective: To study the relationship between the weight change trend of initial treatment patients with pulmonary tuberculosis and the dose change trend of isoniazid, and therefore to analyze the appropriate dose of isoniazid. Methods: Data of initial treatment inpatients with pulmonary tuberculosis from May 1955 to December 2012 were retrospectively analyzed. Elderly patients with pulmonary tuberculosis, patients with drug-resistant tuberculosis, extrapulmonary tuberculosis and those with complications were excluded from the study. The time period was separated as 20th century 1950s to 1960s, 1970s, 1980s, 1990s, 21th century 2000s and 2010s. Samples were selected in each year and month between 1950s to 1960s and 1970s. After 1980s, samples of 1 year were taken from each 5 years. The sex, age and weight for every patient were collected, as well as the dose of isoniazid of every inpatient on a day in therapeutic regimen. Meanwhile, the weight change trend of the patients in different ages and the dose change trend of isoniazid were compared. The total number of cases was 1 398, with 924 males and 474 females, averaging (36.7±14.4) years old. Results: The weight of the patients increased when it was compared between that in 1950s to 1960s, 1970s or 1980s and that in 2000s, with a increasing weight of 3 kg, 3.5 kg and 3 kg respectively. The difference showed statistical significance ( P <0.003). The difference was also significant when the weight in 70s was compared with that in 2010s ( P =0.002). The therapeutic dose of isoniazid remained invariable regardless of the weight change. At 1990s, 2000s and 2010s, the dose of isoniazid per kilogram of body weight would reduce to 0.005 4 g, 0.005 2 g and 0.0054 g relative to patients' weight increase, and the difference was statistically significant ( P <0.001). Conclusions: The weight of pulmonary tuberculosis inpatients increased in recent 60 years. The weight has a close relation with the dose of isoniazid. A fixed dose of isoniazid (0.3 g/d) regardless of the weight change could result in low blood drug concentration . To avoid tolerance of isoniazid and increase the cure rates of pulmonary tuberculosis, the dosage of isoniazid should be increased based on the weight increase of patients.