The word diphenhydramine is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 31
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (50 words)
adenine, adhered, admired, amended, amender, dandier, deadmen, deaired, deanery, demirep, denarii, diamine, diandry, diehard, dienyne, dihedra, drained, draymen, dreamed, enamine, epiderm, hairpin, handier, hayride, headier, headmen, headpin, hennaed, heparin, hydride, impeded, meadery, meander, midyear, nymphid, penname, pinhead, premade, pyramid, readied, reamend, redhead, remined, renamed, repayed, repined, ripened, yardmen, yearend, yearned