It should not be insufflation. Intranasal administration is a synonym for nasal administration you'll find in many papers, it's older.

Insufflation is actually a misnomer for nasal administration, insufflation is blowing something into a person for medical reasons, not using vacuum to pull it into the body.

Now, it's a common misnomer, which I generally let pass without correction. But sauce for the goose is sauce for the gander!