Substituted piperidine compounds represented by the structure I are provided, ##STR00001## wherein each of R.sub.1a, R.sub.1b, R.sub.1c, R.sub.1d, R.sub.1e, R.sub.1f, R.sub.1g, R.sub.1h, R.sub.2, R.sub.2A, R.sub.3, R.sub.4, A, X, a, x and n is as defined in the specification. Substituted piperidine compounds of structure I may permeate or penetrate across a nerve cell membrane into the interior of a nerve cell, may inhibit intracellular Rho kinase enzyme found in nerve cells in mammals, and may find utility in repair of damaged nerves in the central and peripheral nervous system of such mammals. These compounds may induce the regeneration or growth of neurites in mammalian nerve cells and may thereby induce regeneration of damaged or diseased nerve tissue. These compounds also find additional utility as antagonists of the enzyme Rho kinase in treatment of disease states in which Rho kinase is implicated. Pharmaceutical compositions containing these substituted piperidine compounds may be useful to promote neurite growth and in the treatment of diseases in which Rho kinase inhibition is indicated.