What if she injected chloroform into Caylee's mouth? (I will go back to the thread and see if you covered this already...)
http://www.inchem.org/documents/pims/chemical/pim121.htm#SectionTitle:2.2
"Acute poisoning with chloroform is uncommon. The main
route of exposure is inhalation but in some cases poisoning
is due to ingestion; skin absorption is limited. Central
nervous system depression is the most prominent sign after
acute exposure. Death may occur within few minutes of heavy
exposure from respiratory arrest or from ventricular
fibrillation (cardiac arrest). The prognosis is favourable if
consciousness is recovered but liver and kidney damage may
then develop. Less severe exposure causes dizziness, dilated
pupils, nausea, vomiting"