In period II, there was observed no pre-dose drug concentrations, which indicates that the washout period of 48 hours was sufficient.

The pharmacokinetic parameters for test and reference products are summarised in Table 2 , the geometric least square means, ratios and 90% CIs are summarised in Table 3 . Average plasma concentration-time curves and average ln plasma concentration-time curves of test and reference products for single dose of Favipiravir are displayed in Figure 1 and 2 , respectively.

For Test and Reference products, the mean±sd of C_maxwere found 5411.624±2025.680 ng/mL and 5002.171±1231.177 ng/mL, and the mean±sd of AUC_0-tlast were found 9641.989±2545.142 hr.ng/mL and 9907.170±2423.528 hr.ng/mL, respectively (Table 2 ).

The primary target variables data demonstrate the bioequivalence of test and reference products with regard to 90% CI for C_maxof 92.92–119.89 and for AUC_0-tlast of 94.00-99.77, which are within acceptance limits (80.00-125.00%) [4]. The geometric mean ratios were found as 105.55% and 96.84% for C_max and AUC_0-tlast, respectively (Table 3 ).

For the secondary endpoint data, the median of t_max for Test and Reference product were found 0.50 hr and 0.75 hr, respectively and ranged from 0.17 hr to 1.66 hr for test product and 0.17 hr to 2.5 hr for reference product. Besides, the mean±sd of t_1/2for Test and Reference product were found 1.266±0.251 hr (ranged from 0.867 hr to 1.998 hr) and 1.319±0.245 hr (ranged from 0.907 hr to 2.072 hr), respectively. The mean±sd of λ_z for Test and Reference product were 0.566±0.099 1/hr (ranged from 0.347 1/hr to 0.799 1/hr) and 0.542±0.094 1/hr (ranged from 0.334 1/hr to 0.764 1/hr), respectively (Table 2 ).

Table 2. The arithmetic mean±sd of pharmacokinetic parameters of single oral dose of 200 mg Favipiravir in test drug (Favicovir 200 mg Film Tablet, Atabay Kimya San. ve Tic. A.Ş.-Turkey) and reference drug (Avigan 200 mg Film Tablet, Toyama Chemical Industry Co.Ltd.-Japan) in healthy adult male subjects under fasting conditions.^a