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.