Biquelle XL is a brand name for the extended-release formulation of quetiapine, a medication primarily used in the treatment of certain mental health conditions such as schizophrenia, bipolar disorder, and major depressive disorder in adults. As an atypical antipsychotic, Biquelle XL works by altering the actions of chemicals in the brain to help restore the balance of neurotransmitters, thereby improving mood, thinking, and behavior. The extended-release form of the medication allows for once-daily dosing, providing a more consistent release of the drug into the bloodstream over time, which can help in managing symptoms more effectively and improving patient compliance. Like all medications, it may have side effects and should be taken under the guidance of a healthcare professional.