For the first time in history, a Nigerian pharmacist has unravelled the mystery behind the varied reactions of patients of African descent to risperidone, a popular antipsychotic used in the treatment of several mental illnesses.
Pharmacist Oyinlade Kehinde, a PhD student at the University of Florida, USA, and former assistant director of Pharmacy, Federal Neuro-Psychiatric Hospital, Yaba, Lagos, embarked on the groundbreaking study with her co-investigators to demystify why patients react differently to the same psychotropic medications, with some experiencing severe side effects.
Presenting the findings of her breakthrough research titled, “Closing the Health Inequity Gap: Impact of CYP2D6*17 and *29 Alleles on Metabolism in an African Paediatric Population,” at the Yaba International Research Conference 2025, held at the Neuro-Psychiatric Hospital, Yaba, Lagos, Kehinde revealed that the research represents the first and largest real-world study examining African-specific CYP2D6 variants and their impact on risperidone metabolism in children.
The major finding of her research, which earned 2nd Runner-Up at the conference, was that the current Clinical Pharmacogenetics Implementation Consortium (CPIC) activity scores for CYP2D6*17 and CYP2D6*29 may not accurately reflect their effects on risperidone metabolism in African populations.
“Specifically, we found that CYP2D6*17 showed increased activity (activity score of 2), while CYP2D6*29 showed no activity (activity score of 0),” she disclosed. “This differs from existing CPIC classifications, which were primarily based on European data.”
The study focused on risperidone, an antipsychotic commonly used to treat schizophrenia, bipolar disorder, and autism-related irritability. The drug is primarily metabolised by the CYP2D6 enzyme, which has numerous genetic variants. Among people of African ancestry, the CYP2D6*17 and CYP2D6*29 alleles are particularly common and have been known to exhibit reduced activity.
Highlighting the significance of the study, Pharm. Kehinde noted that pharmacogenetic research has largely centred on European populations, leaving major gaps in understanding African genetic diversity—even though individuals of African descent possess the greatest genetic variation globally.
Another unique aspect of the investigation, according to the researcher, was that most existing data on these variants were derived from studies involving drugs other than risperidone, leaving uncertainty about their true effect on risperidone metabolism. “We therefore aimed to determine how CYP2D6*17 and CYP2D6*29 influence risperidone metabolism and whether they are linked to specific adverse drug reactions.”
Beyond scientific discovery, the psychiatric pharmacist emphasised that one of the most meaningful aspects of the study was ensuring that the pharmacogenetic results were returned to the children’s medical records. “This allows healthcare providers to use the information to guide future treatment decisions, ensuring safer and more effective care—a step toward equitable precision medicine in Nigeria.”
Speaking in an exclusive interview with Pharmanews shortly after her virtual presentation at the conference, the former Assistant Director of Pharmacy at the Federal Neuro-Psychiatric Hospital shared her motivation for embarking on the study. “As a clinical pharmacist, I often faced the persistent challenge of patients responding very differently to the same psychotropic medications, with some experiencing severe side effects. Witnessing the emotional and financial toll this placed on patients and their caregivers, as well as the frustration among psychiatrists struggling to make the right treatment decisions, deeply moved me.
“I wanted to understand why these differences existed and find a way to make treatment safer and more effective. That curiosity led me to pharmacogenetics, the study of how our genes influence our response to medications,” she narrated.
Despite the limited training opportunities in pharmacogenetics in Nigeria, the PhD scholar refused to be deterred. She immersed herself in the global scientific community, joining the Pharmacogenomics Global Research Network (PGRN). Through this platform, she collaborated with Dr Laura Ramsey from Children’s Mercy Hospital, Kansas, and Dr Akinyemi Oni-Orisan from the University of California, San Francisco. “Together, we conducted this study at the Child and Adolescent Mental Health Service of the Federal Neuro-Psychiatric Hospital, Yaba.”
She further highlighted the economic benefits of the study, noting that since pharmacogenetic testing costs between $300 and $1,000 per patient, being able to conduct this work locally represents a major breakthrough for a country with limited resources. Ultimately, the findings bring Nigeria closer to ensuring that every patient—regardless of ancestry or geography—receives the right medication at the right dose.
The PhD scholar at the University of Florida expressed her profound gratitude to the Medical Director of the hospital, Dr Olugbenga Owoeye, as well as the pharmacy and laboratory departments, research assistants, and everyone who contributed to the study. “I am deeply grateful to Dr Laura Ramsey and Dr Akinyemi Oni-Orisan, my mentors and co-investigators, whose dedication and passion made this research possible despite the challenges we faced.”
