  Using the Fokker-Planck equation we have studied the drag co-efficient $A(t)$
and the consequent shift $\Delta p_\perp (L)$ in the transverse momentum due to
collisional energy loss of energetic partons while passing through a chemically
equilibrating quark-gluon plasma. Based on these we estimate the quenching
factor $Q(p_\perp)$ when the medium is undergoing longitudinal expansion
governed by master rate equations. In contrast to the case of chemically
equilibrated plasma investigated earlier by Mustafa and Thoma \cite{mus} we
find less quenching because our calculated $Q(p_\perp)$ is always greater at
all momenta. This result is attributed to the weak drag coefficient operating
during initial state interactions.
