Fluorescence detection of tramadol in healthy Chinese volunteers by high-performance liquid chromatography and bioequivalence assessment

Figures & data

Figure 1 Chromatograms of tramadol in plasma.

Notes: (A) Blank plasma; (B) standard plasma sample; (C) plasma sample after dosing. 1, Tramadol; 2, internal standard; 3, O-desmethyltramadol.

Figure 2 In vitro release profiles of tramadol from the test and reference (50 mg).

Notes: ⋄, Tablets; △, capsules. Release experiments were carried out in 0.1 M (HCL solution), at 37°C±0.5°C. Each point represents the mean value of six different experiments ± standard deviation.

Table 1 Pharmacokinetic parameters of the two formulations

Parameter	Formulations
	Tablets	Capsules
t½α (hours)	1.8±0.6	1.9±0.5
t½β (hours)	7.2±1.2	7.9±1.4
Cmax(ng/mL)	532.7±64.2	576.4±68.5
AUC0–T(ng·h/mL)	4,580.8±1,176.3	4,707.3±1,092.4
AUC0–∞(ng·h/mL)	4,726.3±1,278.5	4,864.1±1,176.5
MRT (hours)	9.21±2.4	10.14±2.9
CL (L/h)	27.3±7.7	28.5±6.9

Abbreviations: t_½, half-life; C_max, maximum concentration; AUC, area under the curve; MRT, mean residence time; CL, clearance.

Table 2 Statistical comparison of the two formulations

Parameter	Geometric mean ratio of test/reference drug (90% CI)	% CV
AUC0–t(ng·h/mL)	100.2% (95.3%–103.4%)	16.4%
AUC0–∞(ng·h/mL)	99.6% (94.2%–102.7%)	17.2%
Cmax(ng/mL)	100.8% (93.1%–106.4%)	19.6%

Abbreviations: CI, confidence interval; CV, coefficient of variations; AUC, area under the curve; C_max, maximum concentration.

Figure 3 Mean plasma concentration–time profiles of tramadol from the test and reference in healthy male Chinese volunteers (50 mg).

Note: Each profile represents the mean ± standard deviation of ten volunteers.