18 200 mg giver ikke øget effekt, men incidensen af bivirkninger (hovedpine, flushing, svimmelhed, dyspepsi, tilstopning af næsen, synsforstyrrelser) øges.
Doses of 200 mg did not result in increased efficacy but the incidence of adverse reactions (headache, flushing, dizziness, dyspepsia, nasal congestion, altered vision) was increased.