A restricted class of OTC drugs also exists in the U.S. This restricted class includes drugs such as pseudoephedrine, emergency contraception, and some Schedule V controlled substances. These products, while considered OTC, are kept behind the pharmacy counter and must be dispensed by a pharmacist pursuant to proper identification, age verification, and patient education.
The lux (symbol: lx) is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface.
Unit of length. The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second. Unit of mass. The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram. Unit of time. 1. The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12; its symbol is mol..