  A nonpolynomial one-dimensional quantum potential in the form of an isotonic
oscillator (harmonic oscillator with a centripetal barrier) is studied. We
provide the non-relativistic bound state energy spectrum E_{n} and the wave
functions {\psi}_{n}(x) in terms of the associated Laguerre polynomials in the
framework of the Nikiforov-Uvarov method. Under the spin and pseudospin
symmetric limits, the analytic eigenvalues and the corresponding two-component
upper- and lower-spinors of the Dirac particle are obtained, in closed form.
