708.5  Administering harmful substances.
  Any person who administers to another or causes another to take, without the other person’s consent or by threat or deception, and for other than medicinal purposes, any poisonous, stupefying, stimulating, depressing, tranquilizing, narcotic, hypnotic, hallucinating, or anesthetic substance in sufficient quantity to have such effect, commits a class “D” felony.
[C79, 81, §708.5]

See also chapters 124, 126, and 205