Let A be an F-central simple algebra of degree
$m^2=\prod _{i=1}^k p_i^{2\alpha _i}$
and G be a subgroup of the unit group of A such that
$F[G]=A$
. We prove that if G is a central product of two of its subgroups M and N, then
$F[M]\otimes _F F[N]\cong F[G]$
. Also, if G is locally nilpotent, then G is a central product of subgroups
$H_i$
, where
$[F[H_i]:F]=p_i^{2\alpha _i}$
,
$A=F[G]\cong F[H_1]\otimes _F \cdots \otimes _F F[H_k]$
and
$H_i/Z(G)$
is the Sylow
$p_i$
-subgroup of
$G/Z(G)$
for each i with
$1\leq i\leq k$
. Additionally, there is an element of order
$p_i$
in F for each i with
$1\leq i\leq k$
.