The synthesis and pharmacological activities of a new series of piperazinyl quinazolin-4-(3<i>H</i>)-one derivatives acting toward the α2δ-1 subunit of voltage-gated calcium channels (Ca<sub>v</sub>α2δ-1) are reported. Different positions of a micromolar HTS hit were explored, and best activities were obtained for compounds containing a small alkyl group in position 3 of the quinazolin-4-(3<i>H</i>)-one scaffold and a 3-methyl-piperazin-1-yl- or 3,5-dimethyl-piperazin-1-yl-butyl group in position 2. The activity was shown to reside in the <i>R</i> enantiomer of the chain in position 2, and several eutomers reached single digit nanomolar affinities. Final modification of the central scaffold to reduce lipophilicity provided the pyrido[4,3-<i>d</i>]pyrimidin-4(3<i>H</i>)-one <b>16RR</b>, which showed high selectivity for Ca<sub>v</sub>α2δ-1 versus Ca<sub>v</sub>α2δ-2, probably linked to its improved analgesic efficacy-safety ratio in mice over pregabalin.