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 only found in insects. Neurotransmitters control the heart rate and metabolism. Fleas, ticks, mosquitos and bed bugs produce a neurotransmitter called octopamine. NeuroRX blocks the octopamine, causing a complete shut down of the central nervous system... killing insects nearly instantaneously.