The effect of diabetes mellitus on the pharmacokinetics of TB Drugs in Tanzanian patients Charles Mtabho Meatu District Council Meatu, Simiyu- Tanzania AMREF’s First International Health Conference (From Evidence to action:Lasting change for Africa) Monday 24 th – Wednesday 26 th November 2014 Nairobi-Kenya Safari Park Hotel 7/2/20151

Introduction  Diabetes mellitus is a well-known risk factor for TB  With the global increase in cases of type 2 DM, the association between TB and DM is re-emerging  TB is more difficult to treat in diabetic patients — less favourable response to TB treatment 7/2/20152

……introduction  DM patients have lower plasma concentrations of certain drugs 1,2  Absorption, distribution, metabolism and/or excretion of drugs are changed  If this also applies to anti-TB drugs, this may at least partly explain the slower response to TB treatment in patients with DM 1.Gwilt et al. (1991). Clin Pharmacokinet 2.Dostalek et al. (2012) Clin Pharmacokinet 7/2/20153

……introduction  Indonesian study1- exposure to rifampicin was 53% lower in patients with TB and DM, compared with patients with TB only 3 —this was attributed to DM and to the higher weight of patients with DM  Indonesian study2- no differences in drug exposure 4  Peruvian study- No difference in PK parameters 5 3.Nijland et al. Clin Infect Dis Ruslami et al. AAC Requena-Mendez et al AAC /2/20154

……introduction  These findings need more research – Ethnic differences – Study African TB patients because the African continent has the highest TB incidence and mortality rates Tanzania in 2012, the incidence rate of TB was 169 per 100,000 population The diabetes prevalence in adults is estimated at 7.8% in /2/20155

Methods  Study design -observational pharmacokinetic study  20 TB patients without DM and 20 TB patients with DM were recruited at Mawenzi Hospital as well as other hospitals around the region which treat TB  TB was diagnosed according to the Tanzanian guideline and practice- clinical symptoms and signs, chest x-ray examination, sputum smear microscopy  Diabetic patients were included if they had a previously established diagnosis of DM and diagnosis was confirmed at the time of PK sampling 7/2/20156

……methods  Patients with a body weight above 50 kg received 4 FDC tablets daily (300 mg INH, 600 mg RIF, 1600 mg PZA and 900 mg ETH), those below 50 kg received 3 FDC tablets (225 mg INH, 450 mg RIF, 1200 mg PZA and 675 mg ETH)  Diabetic patients were either on dietary management alone, or oral hypoglycaemic agents and/or injectable insulin. 7/2/20157

……methods  Sample collection – PK sampling done after 2 weeks, given the expected steady state of the drugs – Patients fasted at least 8hrs before drug intake and took a standardised breakfast within 30 minutes after drug intake – Serial venous blood samples before, and at 1, 2, 3, 4, 6, 8, 10 and 24 hours after observed TB drug intake – Plasma was separated and kept frozen at -80 o C 7/2/20158

……methods  Pharmacokinetic analysis – Plasma concentrations of INH, acetylisoniazid, RIF, desacetylrifampicin, PZA & ETH were assessed by validated high-performance liquid chromatography (HPLC) – Pharmacokinetic evaluations were performed using non- compartimental methods in WinNonLin – PK parameters; C max, T max, AUC 0-24h, T 1/2, CL, Vz 7/2/20159

……methods  Statistical analysis – Data was presented as mean (SD), median (IQR) – Comparison of subgroups - two-sample t-test or Wilcoxon rank-sum test  Univariate and Multivariate analyses to assess the effects of age, sex, body weight, dose in mg/kg, HIV status, acetylator status, fasting plasma glucose and HbA1c on the AUC 0-24h and C max of the four first-line TB drugs  All statistical analyses were performed using SPSS version 20 (SPSS Inc, Chicago II). 7/2/201510

Results ParameterTB-DMTBP-value Sex (female, n[%])5[25%]4[20%] 0.705** Age (years; median[IQR])49(40-56)38(30-42) 0.001* Body weight (kg; mean[SD]) 58.7(12.3)55.7(6.4) BMI(kg/m 2 mean[SD])20.6(4.0)19.5(2.4) TB drugs Dose per kg (mg/kg, mean[SD]) Rifampicin 9.8(1.4)10.4(0.9) Isoniazid 4.9(0.7)5.2(0.5) Pyrazinamide25.5(3.8)27.8(2.4) Ethambutol18(2.5)19.1(1.7) FBG(mmol/L, median(IQR))15.9( )6.95( ) <0.001* HIV positive, n(%) 7(35%) - HBA1c(mmol/mol; mean[SD])106.4[22.7]- - *Mann-Whitney U test **chi square test 7/2/201511

Pharmacokinetic parameters of tuberculosis drugs in Tanzanian diabetic and non-diabetic TB patients in northern Tanzania Drug/PK parameter TB-DMTB p-value Rifampicin AUC 0-24, h*mg/L29.91[1.77]39.91[1.26]0.044 Cmax, mg/L 7.92[1.71] 8.92[1.28]0.373 Proportion with Cmax below reference range, n[%] c 9[47.4] 7[35.0]0.433 Tmax, h[IQR] b 2.12[ ] 1.08[ ]0.027 T1/2, h 1.44[1.30] 1.80 [1.38]0.026 Vz, L38.74[1.79]37.30 [1.31]0.794 CL, L/h18.60[1.74]14.40 [1.24]0.063 Isoniazid AUC 0-24, h*mg/L 5.41[2.61]10.61[1.94]0.015 Cmax, mg/L 1.65[2.15] 2.77[1.45]0.010 Proportion with Cmax below reference range, n[%] c 14 [73.7]11 [55.0]0.224 Tmax, h[IQR] b 1.03[ ] 1.07[ ]0.855 T1/2, h 2.55[1.51] 2.54[1.61]0.985 Vz, L188.78[2.26]99.19[1.26]0.002 CL, L/h 51.31[2.78]26.89[1.84] /2/201512

Geometric mean steady-state plasma concentration-time profiles of rifampicin, isoniazid, pyrazinamide, and ethambutol in TB-DM patients (solid line graph, n=19) and TB only patients (dotted graph, n=20) 7/2/201513

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….. results  Based on the metabolic ratio of acetylisoniazid concentration over isoniazid concentration at 3 hours post dose – 55.6% of the diabetic versus 47.4% of the non-diabetic TB patients were fast acetylators. The difference was not statistically significant (chi square = 0.248, p value 0.618) 7/2/201515

….. results Univariate analysis  Analysis of the association between PK parameters AUC 0-24 and C max of the TB drugs and explanatory variables (age, sex, body weight, dose per Kg, HIV status, acetylator status, FBG, HbA1c) —Age significantly correlated only with C max of isoniazid (Spearman’s rho = , p = 0.014) —Fast acetylators had significantly lower AUC 0-24 (geometric means 4.1 versus 16.2 h*mg/L, p = <0.001) and C max (1.6 versus 3.1 mg/L, p = 0.001) values of isoniazid than slow acetylators 7/2/201516

….. results  In a multiple linear regression analysis with age, sex, dose per kg, HIV status and acetylator status DM remained an independent predictor of the PK of isoniazid and rifampicin  All PK parameters for Pyrazinamide and Ethambutol were not significantly different between diabetic and non-diabetic TB patients 7/2/201517

Discussion/conclusion  First report describing (PK) parameters of TB drugs in diabetic and non-diabetic TB patients using intensive PK sampling in an African population  Similar studies in Indonesia and Peru have shown contradicting results —Indonesian study-1 concluded that DM was associated with a strong decrease in plasma concentrations of rifampicin —Indonesian study-2, no significant difference —Peruvian study- no significant difference 7/2/201518

…. discussion/conclusion  Our study —distinctively different ethnic population —intensive (9 sampling points over 24 hrs) PK sampling —All 4 standard TB drugs in 40 patients, with validated methods  Indonesian study2 concludes weight differences between diabetic and non-diabetic TB patients were basis for low PK —Although we did not match our patients for body weight, the distribution of body weight the same between diabetic and non-diabetic TB patients —body weight was no predictor of exposure to TB drugs in our multiple linear regression analyses 7/2/201519

…. discussion/conclusion  There is no evidence that antidiabetic drugs lower the concentration of TB drugs  We believe the differences in PK are due to DM  Substantiated by similar associations that we found between FBG levels and exposure to rifampicin and isoniazid in our population 7/2/201520

…. discussion/conclusion  Since increasing the dose of TB drugs may result in increased plasma concentrations of the drugs and improved treatment outcome; —Individualization of the dosages and therapeutic drug monitoring in diabetic TB patients are necessary —Or in developing countriesincreasing the doses of TB drugs (especially rifampicin and isoniazid) in the whole population of diabetic —To this end, higher doses of TB drugs have been shown to be safe and tolerable 7/2/201521

Study limitations  Unequal age distribution between the groups – Age has been found not to be associated with pharmacokinetics of TB drugs in many studies  We didn’t match for sex and weight – however the distribution of the parameters was the same in the two groups – Age, gender and dose/kg were no significant predictors in multiple regression analyses  The number of patients (n=39) may be high for a PK study with intensive PK sampling, yet is relatively low for multiple regression with several explanatory variables 7/2/201522

Acknowledgements – Study participants – Staff at Mawenzi Hospital and KCMC – Laboratory technicians at the Department of Clinical Pharmacy of the Radboud University Medical Centre Nijmegen in the Netherlands for their technical support Financial support – African Poverty Related Infection Oriented Research Initiative (APRIORI), a research network grant from the Netherlands Foundation for the Advancement of Tropical Research (NWO-WOTRO) – PANACEA – UNESCO 7/2/201523

Thank you 7/2/201524