  In this paper we analyze two higher-derivative theories, the generalized
electrodynamics and the Alekseev-Arbuzov-Baikov's effective Lagrangian from the
point of view of Faddeev-Jackiw sympletic approach. It is shown that the full
set of constraint is obtained directly from the zero-mode eigenvectors, and
that they are in accordance with known results from Dirac's theory, a remnant
and recurrent issue in the literature. The method shows to be rather economical
in relation to the Dirac's one, obviating thus unnecessary classification and
calculations. Afterwards, to conclude we construct the transition-amplitude of
the non-Abelian theory following a constrained BRST-method.
