Benzodiazepines are one of the most commonly used anxiolytic and anticonvulsant drugs in the world.
For nearly all the current benzodiazepines, their toxic effects on different organs have not been fully de
scribed. The aim of the current work was to study the immurwlogic and vascular changes induced by
short term chronic administration ofalprazolam and clonazepam in non stressed and stressed adult male
albino rats. Forty two adult male albino rats were divided imo 6 groups (1): (Ia) Negative control, (Jb):
Positive control rats received distilled water, (ll): Stressed rats, (Ill): Non stressed rats received daily
oral dose of clonazepam (05mglkg), (IV) : Stressed rats received daily oral dose of clonazepam
(05mglkg), (V): Non stressed rats received daily oral dose of alprazoiAm (0.3mglkg). (Vl): Stressed rats
received daily oral dose of alprazolam (03mglkg). At the end of the 4th week total leukocyte count
(WBCs) and differential count were detected. anti-sheep RBC antibody (Anti-SRBC) titer and interleu
kin-2 (IL-2) level were assessed, thymus glands, lymph nodes, spleens and abdominal aortae were submit
ted to histopathological examination. It was found that alprazolam induced a significant increase in the
neutrophils count and a significanl decrease in the lymphocytes, anti-SRBC titer and IL-2 level with se
vere depletion of the splenic, thymal and nodal lymphocytes, accompwtied by congestion and eosinophilic
vasculitis of all rested organs in comparison to c/onazepam treated raJs. The previous toxic effects were
worsened by stress. It was concluded that immune system and blood vessels can be adversely affected by slwrt term chronic administraJion of alpraz.olam to a greater extent than clonazepam and these toxic ef
fects are aggravated by stress.