Pharmacokinetics of a novel sublingual spray formulation of the antimalarial drug artemether in healthy adults

The pharmacokinetics of sublingual artemether (ArTiMist) was investigated in two open-label studies. In study 1, 16 healthy males were randomized to each of four single-dose treatments administered in random order: (i) 15.0 mg of sublingual artemether (5 × 3.0 actuations), (ii) 30.0 mg of sublingual artemether (10 × 3.0 mg), (iii) 30.0 mg of sublingual artemether (5 × 6.0 mg), and (iv) 30.0 mg of artemether in tablet form. In study 2, 16 healthy males were randomized to eight 30.0-mg doses of sublingual artemether given over 5 days as either 10 3.0-mg or 5 6.0-mg actuations. Frequent blood samples were drawn postdose. Plasma artemether and dihydroartemisinin levels were measured using liquid chromatography-mass spectrometry. Population compartmental pharmacokinetic models were developed. In study 1, sublingual artemether absorption was biphasic, with both rate constants being greater than that of the artemether tablets (1.46 and 1.66 versus 0.43/h, respectively). Relative to the tablets, sublingual artemether had greater bioavailability (≥1.24), with the greatest relative bioavailability occurring in the 30.0-mg dose groups (≥1.58). In study 2, there was evidence that the first absorption phase accounted for between 32% and 69% of the total dose and avoided first-pass (FP) metabolism, with an increase in FP metabolism occurring in later versus earlier doses but with no difference in bioavailability between the dose actuations. Sublingual artemether is more rapidly and completely absorbed than are equivalent doses of artemether tablets in healthy adults. Its disposition appears to be complex, with two absorption phases, the first representing pregastrointestinal absorption, as well as dose-dependent bioavailability and autoinduction of metabolism with multiple dosing.