Biological implications and therapeutic potential of phosphodiesterase inhibitors: A review

Phosphodiesterase (PDE) inhibitors regulate cyclic adenosine monophosphate and cyclic guanosine monophosphate pathways, which influence neurodevelopment, cardiovascular function, and immune responses. Multiple PDE families exist, classified as dual-substrate (PDE1, PDE2, PDE3, PDE10, PDE11) or non-dual-substrate (PDE4, PDE5, PDE6, PDE7, PDE8, PDE9), each with distinct biological roles. This review summarizes the therapeutic applications of PDE inhibitors, evaluates evidence across different disease domains, and highlights challenges and future research priorities. A narrative review of published studies and clinical trial data was conducted, focusing on pharmacological properties, therapeutic relevance, and safety profiles of PDE inhibitors. Sources included PubMed, ClinicalTrials.gov, and regulatory reports. Dual-substrate PDEs demonstrate therapeutic potential in Alzheimer disease (PDE1), anxiety and memory enhancement (PDE2), and heart failure (PDE3), although chronic PDE3 inhibition may increase risks. Non-dual-substrate PDEs, such as PDE4 and PDE5, are clinically established for asthma, chronic obstructive pulmonary disease, psoriasis, erectile dysfunction, and pulmonary hypertension. Advances in structure-activity relationship studies have produced more selective and potent inhibitors. However, adverse effects, such as nausea (PDE4 inhibitors) and cardiovascular risks (long-term PDE3 inhibitors), remain limiting factors. PDE inhibitors represent a rapidly evolving therapeutic class with broad clinical applications. Their further development requires strategies to minimize adverse effects, improve selectivity, and better define disease-specific roles. Future research should focus on precision medicine approaches to fully harness their therapeutic potential.