JNTU B.Pharmacy III SCREENING METHODS IN PHARMACOLOGY Previous Question Paper (February/March-2022 - R17)

Mice (Mus musculus) are the most widely used laboratory animals in pharmacological research due to their small size, short life cycle, and well-characterized genome. Their primary uses include:

• Genetic Research: Mice are the preferred model for creating transgenic and knockout strains to study gene function and human disease mechanisms.
• Drug Screening: They are used for initial screening of pharmacological agents, including analgesic, anti-inflammatory, and psychopharmacological studies.
• Immunology and Oncology: Mice are essential for studying immune responses, vaccine development, and tumor growth in xenograft models.
• Toxicology: They are employed for acute and chronic toxicity testing, as well as teratogenicity and mutagenicity studies.
• Advantages: Their rapid reproductive rate, ease of handling, and the availability of standardized inbred strains make them cost-effective and highly reproducible models for comparative medicine.

The Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA) mandates that euthanasia must be performed humanely, minimizing pain, distress, and anxiety. Approved methods include:

• Inhalation Methods: Use of carbon dioxide (CO2) gas is common for small rodents. It must be administered gradually in a chamber to avoid respiratory distress. Following CO2 exposure, a secondary physical method, such as cervical dislocation, is often required to ensure death.
• Chemical Methods: Overdose of barbiturates (e.g., pentobarbital sodium) administered via intraperitoneal or intravenous routes is the preferred method for many species. This induces rapid loss of consciousness followed by cardiac and respiratory arrest.
• Physical Methods: Cervical dislocation is permitted for small rodents if performed by trained personnel, ensuring immediate unconsciousness. Decapitation is allowed only when scientifically justified and performed with sharp, well-maintained equipment.
• General Requirements: Euthanasia must be performed by trained staff. The animal must be monitored until death is confirmed by the absence of heartbeat, respiration, and corneal reflex. The disposal of carcasses must comply with institutional biosafety and environmental regulations.