BioShield?is powered by NeuroRX?. NeuroRX?was developed by pharmacists with Prescription Strength results and is a proprietary formula of Portland Outdoors?. NeuroRX?works by attacking a neurotransmitter found only in insects. Neurotransmitters control the heart rate and metabolism. Fleas, ticks, mosquitoes and bed bugs produce a neurotransmitter called octopamine. NeuroRX? blocks the octopamine, causing a complete shutdown of the central nervous system killing insects nearly instantaneously. Octopamine is found only in insects. Humans and other mammals, birds and fish do not produce octopamine. NeuroRX? is safe to use around children and pets but is deadly to insects when used as directed.