We study existence, multiplicity and qualitative properties of entire solutions for a noncompact problem related to second-order interpolation inequalities with weights. More precisely, we deal with the following family of equationsis Delta(2)u =lambda vertical bar x vertical bar(-4)u + vertical bar x vertical bar(-beta)vertical bar u vertical bar(q-2)u in R-N, where N >= 5,q > 2,beta = N - q( N - 4)/2 and lambda is an element of R is smaller than the Rellich constant. (C) 2012 Elsevier Ltd. All rights reserved.