COMPARATIVE CNS ACTIVITIES OF CLINICALLY EMPLOYED ANTIHISTAMINES (H1 ANTAGONIST)

Aim: H1 Antihistamines are classified into the first generation and second generation agents. The main differences between the first and second generations of drugs are their propensity to cause central nervous system (CNS) side effects. Therefore, the present study was aimed to analyze the effects of different H1 antihistamines (first and second generation) on CNS using different animal experimental models. Materials and Methods: H1 antihistamines such as pheniramine maleate (3 mg/kg, 6 mg/kg), cetirizine (0.6 mg/kg, 1.2 mg/kg), levocetirizine (0.6 mg/kg, 1.2 mg/kg), loratadine (1 mg/kg, 2 mg/kg) and desloratadine (0.6 mg/kg, 1.2 mg/kg) are evaluated and compared for their effects on CNS using experimental animal model (Pentobarbitone sleeping time, spontaneous motor activity, motor coordination) in Swiss albino mice. Results and Discussion: Desloratadine (0.6 mg/kg, 1.2 mg/kg) and loratadine (1 mg/kg, 2 mg/kg) did not produce significant (P<0.05) effect on sleeping time when compared to control. At 120 min time interval after treatment with cetirizine (1.2 mg/kg) and levocetirizine (1.2 mg/kg) was shown a reduction in locomotor activity and remaining three drugs such as pheniramine (6 mg/kg), loratadine (2 mg/kg) and desloratadine did produce any effect on locomotor activity. Treatment with a higher dose of pheniramine (6 mg/kg) and cetirizine (1.2 mg/kg) was shown significant (P<0.05) motor coordination while other drugs did not induce any motor in-coordination. First generation antihistamines were shown a significant effect on CNS activity at low and high dose while only some second-generation antihistamines showed a significant effect on CNS at the high dose. Conclusion: Numerous well-performed, sensitive measures of psychomotor and cognitive performances are needed to study to compare the effect of the first generation and second generation antihistamines on CNS to avoid serious impairment of CNS function.