1-Alkylazacycloalkan-2-one esters of naproxen were synthesized and assayed to determine their stability in phosphate buffer and isopropyl myristate, susceptibility to undergoing in vitro enzymatic hydrolysis and flux through excised human skin. 1-Methylazacycloalkan-2-one esters of naproxen (I-IV) proved poorly stable both in aqueous media and isopropylmyristate while 1-ethylazacycloalkan-2-one esters (V-VIII) were much more stable. Esters V-VIII were readily hydrolyzed in vitro by porcine esterase and esters V-VI penetrated excised human skin better than the parent drug from aqueous suspensions. On the basis of the results obtained, 1-ethylpyrrolidone and 1-ethylvalerolactam appear to be suitable promoieties for obtaining naproxen dermal prodrugs.