What conventional antipsychotic has relatively little anticholinergic or antihistaminic binding activity?

A. Haloperidol: Haloperidol is a high-potency first-generation antipsychotic with strong D2 receptor antagonism but minimal affinity for muscarinic (anticholinergic) and histamine H1 receptors. This explains why it has fewer sedative and anticholinergic side effects compared with low-potency or atypical antipsychotics. B. Clonazepam: Clonazepam is a benzodiazepine, not an antipsychotic. It acts primarily on GABA-A receptors to produce anxiolytic and anticonvulsant effects and has no relevant anticholinergic or antihistaminic binding in the context of antipsychotic therapy. C. Risperidone: Risperidone is an atypical antipsychotic with moderate antagonism at serotonin 5HT2A and some affinity for H1 and alpha-1 receptors. While it has relatively low anticholinergic activity, it does not match haloperidol’s minimal antihistaminic and anticholinergic profile. D. Clozapine: Clozapine is a low-potency atypical antipsychotic with strong anticholinergic, antihistaminic, and alpha-1 adrenergic receptor binding. These properties contribute to sedation, orthostatic hypotension, and anticholinergic side effects such as dry mouth and constipation.