Lepimectin A4 is a the major analogue of a complex of semi-synthetic milbemycins synthesised from 15-hydroxy-5-ketomilbemycin A3/A4 by coupling to methoxyiminophenylacetic acid and then reducing with sodium borohydride. Commercially, lepimectin is a mixture of lepimectin A3 and A4, generically known as lepimectin, with insecticidal, Acaricide and nematocidal properties. Ananlytical methods for the quantitation of the lepimectins have been published but there is a lack of data on the properties and biological potency of the individual analogues. Like other milbemycins, lepimectin acts by opening glutamate sensitive chloride channels. Lepimectin is marketed in Japan and Korea for use on fruit, vegetable and ornamental plants.