Abstract
INTRODUCTION: Conjoined twins present a rare but clinically challenging scenario requiring highly individualized pharmacologic strategies. Anatomical fusion, shared circulatory systems, and organ overlaps complicate drug absorption, distribution, metabolism, and excretion, including the neonatal intensive care unit setting and perioperative care. This review aims to synthesize current evidence and clinical experience regarding pharmacotherapy in CTs, focusing on drug selection, therapeutic drug monitoring and individualized dosing strategies based on anatomical and physiological variations. METHODS: We performed a comprehensive structured literature review using PubMed database, covering the period 1970-2025, restricted to English-language publications. Case reports and reviews relevant to pharmacology in CTs were included (n = 4/93); surgical, radiological or anesthetic-only reports without pharmacologic content were excluded. We integrated these findings with two case reports involving pygopagus and thoracopagus conjoined twins treated in our tertiary referral care hospital. Key pharmacokinetic variables such as volume of distribution, renal clearance, and enteral absorption were examined in relation to the cross-circulation status. Additionally, an online quiz was conducted among clinicians to assess baseline knowledge. RESULTS: Our results observations suggest that drugs such as amikacin require TDM-based adjustments in the presence of cross-circulation in both subjects. Shared renal or gastrointestinal anatomy further necessitates titrated and monitored dosing regimens. Emergency medication strategies should consider whether complete, partial, or absent circulatory sharing is present. Questionnaire data revealed unexpectedly high knowledge levels among physicians and pharmacists, though further educational enhancements-such as virtual reality simulation and tailored protocols-are recommended. DISCUSSION: Pharmacologic management in CTs demands a multidisciplinary approach, close monitoring, and careful documentation. Case-based strategies and educational reinforcement can reduce risk and improve outcomes. Further research, including the establishment of central registries and the use of physiologically based pharmacokinetic modeling, is essential to inform individualized care in this very rare population.