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Kayhan and Akgüneş 2037
Table 1. Comparison of median serum concentration at 2 h after medication administration as estimate of peak serum concentration
levels and expected range, therapeutic drug monitoring.
Medication Median serum concentration (µg/ml) Expected serum concentration range (µg/ml)
Isoniazid (daily 300 mg) 3.83 ± 2.09 3-6
Rifampicin (daily 600 mg) 6.13 ± 4.27 8-24
Ethambutol (weight adjusted) 3.68 ± 2.41 2-6
Pyrazinamide (weight adjusted) 32.20 ± 16.96 20-50
Table 2. Study variables and their correlation with drug serum concentrations (µg/ml).
Variable
Means± SD or
n
Test used
Age (years) 41.51±16.90 PC
Analysis INH
result
p = 0.160
r = -0.204
Analysis RIF
result
p = 0.193
r = -0.189
Analysis
EMB result
p = 0.726
r = 0.051
Analysis
PZA result
p = 0.106
r = -0.234
Sex (males/females) 31/18 IST p = 0.005 p = 0.000 p = 0.570 p = 0.002
Body mass index (kg/m 2 ) 22.50±4.34 PC
p = 0.006
r = 0.390
p = 0.935
r = -0.012
p = 0.317
r = 0.146
p = 0.139
r = -0.214
Smoking status smoker/ nonsmoker IST p = 0.532 p = 0.004 p = 0.551 p = 0.391
'Drug dose(mg/kg)
Isoniazid 4.49±1.14
Rifampicin 9.92±2.21
Ethambutol 24.16±5.15
Pyrazinamide 28.98±8.65
Serum Albumin (g/dl) 3.87±0.54 PC
Heamoglobin 12.60±1.51 PC
PC
p = 0.000
r = 0.487
p = 0.303
r = -0.150
p = 0.303
r = -0.150
p = 0.039
r = 0.295
p = 0.734
r = -0.012
p = 0.083
r = -0250
Creatinine clearence* 118.73±37.08 PC - -
p = 0.827
r = -0.155
p = 0.889
r = 0.020
p = 0.581
r = 0.081
p = 0.816
r = 0.034
p = 0.005
r = 0.395
p = 0.550
r = -0.087
p = 0.005
r = -0.203
*By Cockcroft-Gault equation: in men= (140-age) × (weight in kg)/ (72 × serum creatinine) and in women = 0.85 × (140-age) × (weight in kg)/(72 × serum
creatinine) used for ethambutol; PC = Pearson correlation; IST = Independent samples T-test.
significantly associated with drug dose (mg/kg) (p =
0.000) and there was a correlation between these two
variables (r = 0.487). 2 h INH concentration was not
associated with age, serum albumin, smoking status and
heamoglobin levels (Table 2).
Serum RIF concentration
The mean serum concentration of RIF was 6.13 ± 4.27
µg/ml and the mean RIF dose was 9.92 ± 2.21 mg/kg
(Tables 1 and 2; Figure 3). The prevalance of a low 2 h
RIF concentration was 75.5% (37/49) in this study (Figure
1) . RIF concentrations did not reach to therapeutic levels
at 6 h in these patients. 2 h RIF concentration showed
difference according to sex (p = 0.000). The mean RIF
concentration of males (4.23 µg/ml) was lower than
females (9.41 µg/ml). By Independent samples T-test
analysis, 2 h RIF concentration was found to be
associated with cigarette smoking (p = 0.004). The mean
serum RIF level of smokers (4.50 µg/ml) was lower than
non-smokers (7.50 µg/ml). 2 h RIF serum concentration
was not associated with the other variables (age, body
mass index, serum albumin, drug dose (mg/kg) and
-