LY-320,135 displays fairly good selectivity, with a binding affinity for CB1 around 70x stronger than for CB2, but both its potency and selectivity are modest compared to newer agents, and at higher doses it also binds to a range of non-cannabinoid receptors. However LY-320,135 is still fairly widely used in research, particularly for elucidating the mechanisms by which many CB1 antagonists act as inverse agonists at higher doses.
^Felder CC, Joyce KE, Briley EM, Glass M, Mackie KP, Fahey KJ, et al. (January 1998). "LY320135, a novel cannabinoid CB1 receptor antagonist, unmasks coupling of the CB1 receptor to stimulation of cAMP accumulation". The Journal of Pharmacology and Experimental Therapeutics. 284 (1): 291–7. PMID9435190.