1. A person commits the offense of delivery of a controlled substance causing serious physical injury, as defined in section 556.061, if a person delivers or distributes a controlled substance under section 579.020 knowing such substance is mixed with another controlled substance and serious physical injury results from the use of such controlled substance.
2. It shall not be a defense that the user contributed to the user's own serious physical injury by using the controlled substance or consenting to the administration of the controlled substance by another.
3. The offense of delivery of a controlled substance causing serious physical injury is a class C felony.
4. For purposes of this section, "controlled substance" means a Schedule I or Schedule II controlled substance, as defined in section 195.017.