In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The drug is known to cause a variety of acute toxic effects , ranging from nausea , restlessness , insomnia , ataxia , slurred speech and nystagmus to mood changes , perceptual alterations , inattention , disorientation and aggressive behavior ( Rammer et al 1988 ; Katona and Watson 1986 ; Isbell and Fraser 1953 ; Devlin et al 1985 ; McCarthy 1971 ; Dodds and Revai 1967 ; Degkwitz 1964 ; Hildebrand et al 1989 ) .
### Output Text:
The drug is known to cause a variety of acute toxic effects , ranging from nausea , restlessness , insomnia , ataxia , slurred speech and nystagmus to mood changes , perceptual alterations , inattention , disorientation and aggressive behavior ( Rammer et al 1988 ; Katona and Watson 1986 ; Isbell and Fraser 1953 ; Devlin et al 1985 ; McCarthy 1971 ; Dodds and Revai 1967 ; Degkwitz 1964 ; Hildebrand et al 1989 ) . 