Pyridoxal‐5‐phosphate plasma concentrations in children receiving tuberculosis chemotherapy including isoniazid

Aim: Little is known about pyridoxine nutriture of children treated with isoniazid (INH) regimens. This study documents plasma pyridoxal 5′‐phosphate (PLP) concentrations in children, HIV‐infected and HIV‐uninfected, receiving INH regimens. Methods: Children from the Western Cape of South Africa hospitalized for tuberculosis (TB) management were studied. Plasma PLP concentrations were determined on enrolment, 1‐month after commencing TB treatment, and again after 4‐month’s treatment. The children received a supplement meeting pyridoxine requirements. Results: Nineteen HIV‐infected and 33 HIV‐uninfected children received INH (dosage range 4–20 mg/kg) daily. Mean PLP plasma concentrations on enrolment were 8.32 (SD 6.75) ng/mL and 11.28 (SD 3.02) ng/mL in HIV‐infected and HIV‐uninfected children, respectively (p = 0.11) and after 4‐month’s treatment 6.75 (SD 2.71) ng/mL and 14.76 (SD 7.96) ng/mL (p < 0.001). On enrolment 9 (50%) HIV‐infected and 5 (15%) HIV‐uninfected children (p = 0.016) had suboptimal PLP concentrations (<6 ng/mL); after 4‐month’s treatment 8 (42%) and 2 (6%) (p = 0.004). Conclusion: Plasma PLP concentrations in children treated for TB were low on enrolment in HIV‐infected and HIV‐uninfected children; after 4‐month’s treatment low values were still common in HIV‐infected children. Additional pyridoxine supplementation of malnourished children treated for tuberculosis is advisable, particularly those HIV‐infected.