Sentry drug is also called Arbor drug. It was founded by Eugene Applebaum and Bruno Manni in 1974.
A sentry drug is a drug which is administered alongside another drug to enhance the latter's activity. The role of sentry drug is to guard or assist the principal drug. Many sentry drugs protect their partner drug by inhibiting an enzyme which metabolizes the latter (e.g. carbidopa and levodopa).
Sentry drugs have also been used to localize the site of action of local anaesthetics and to increase the absorption of drugs from the GIT (e.g. adrenaline & procaine), adrenaline constricts the blood vessels in the surrounding area of the injection and so prevents procaine being rapidly removed from the area by the blood supply.
Smart drugs are drugs, supplements, nutraceuticals, functional foods or any chemical ingested that may improve mental function. Some of these drug improve overall IQ while others are more focused e.g. on memory boosting or attention span or creativity. These substances are also called neuro enhancers, cognitive enhancers, intelligence enhancers or "nootropics."
"Nootropic" comes from Greek - "noos" means mind and "tropos" means changed, toward, turn.
Smart drugs are thought to work by altering the availability of the brains supply of neurochemicals (neurotransmitter, enzymes & hormones) by increasing blood flow to the brain (flooding) thus improving brain’s oxygen supply or by stimulating nerve growth.
Examples of Smart Drugs
Traditional herbs: Vitamin B & D, omega-3, isoflavones
Prescription drugs: Methylphenidate and Dextroamphetamine: Stimulants used to treat attention deficit hyperactivity disorder.
Nutrients: Choline and derivatives: precursor to acetylcholine. eggs, meat and milk are good sources of choline.
Recreational agents: Tetrahydrocannabinol (THC), amphetamine, tobacco.