The name parses as
去氧 (qùyǎng 'deoxy-') +
麻黄碱 (máhuángjiǎn 'ephedrine') — chemically accurate since meth is the deoxy derivative of ephedrine. Street and news media usually use
冰毒 (bīngdú 'ice drug') instead;
去氧麻黄碱 is the formal pharmacological name.