Single ascending dose (SAD) and multiple ascending dose (MAD) studies are typically the first in human studies. They seek to gain information on safety and tolerability, general pharmacokinetic (PK) and pharmacodynamic ( PD) characteristics, and of course identify the maximum tolerated dose (MTD).
Conventionally, SAD and MAD studies were conducted separately, but increasingly are combined into an ‘umbrella’ protocol which addresses both SAD and MAD objectives.