The blood glucose level increased in parallel with the heart rate following cilostazol administration in three diabetic patients

Role of Phosphodiesterase in the Biology and Pathology of Diabetes

Glucose metabolism is the initiator of a large number of molecular secretory processes in β cells. Cyclic nucleotides as a second messenger are the main physiological regulators of these processes and are functionally divided into compartments in pancreatic cells. Their intracellular concentration is limited by hydrolysis led by one or more phosphodiesterase (PDE) isoenzymes. Literature data confirmed multiple expressions of PDEs subtypes, but the specific roles of each in pancreatic β-cell function, particularly in humans, are still unclear. Isoforms present in the pancreas are also found in various tissues of the body. Normoglycemia and its strict control are supported by the appropriate release of insulin from the pancreas and the action of insulin in peripheral tissues, including processes related to homeostasis, the regulation of which is based on the PDE- cyclic AMP (cAMP) signaling pathway. The challenge in developing a therapeutic solution based on GSIS (glucose-stimulated insulin secretion) enhancers targeted at PDEs is the selective inhibition of their activity only within β cells. Undeniably, PDEs inhibitors have therapeutic potential, but some of them are burdened with certain adverse effects. Therefore, the chance to use knowledge in this field for diabetes treatment has been postulated for a long time.

Therapeutic efficacy of pentoxifylline on proteinuria and renal progression: an update

Blood pressure control with renin-angiotensin system (RAS) blockade has remained the gold standard for treating patients with proteinuric chronic kidney disease (CKD) up to date. Nevertheless, RAS blockade slows but does not halt the progression of kidney disease, thus highlighting the need to search for additional therapeutic approaches. The nonselective phosphodiesterase (PDE) inhibitor pentoxifylline (PTX) is an old drug that exhibits prominent anti-inflammatory, anti-proliferative and anti-fibrotic activities both in vitro and in vivo. Studies in human subjects have shown that PTX monotherapy decreases urinary protein excretion, and add-on therapy of PTX to background RAS blockade additively reduces proteinuria in patients with CKD of various etiology. More recent studies find that PTX combined with RAS blockade delays the decline of glomerular filtration rate in diabetic patients with mild to moderate CKD, and reduces the risk of end-stage renal disease in diabetic and non-diabetic patients in late stage of CKD with high proteinuria levels. In this review, we update the clinical trial results of PTX as monotherapy, or in conjunction or in comparison with RAS blockade on patients with proteinuria and CKD, and propose a mechanistic scheme explaining the renoprotective activities of this drug.

Effect of cilostazol in treating diabetes-associated microvascular complications

PURPOSE

Cilostazol (Pletal), a phosphodiesterase-3 inhibitor, was approved in the United States in 1999 to reduce symptoms of intermittent claudication. Cyclic adenosine monophosphate levels increase from inhibition of phosphodiesterase resulting in anti-platelet, anti-inflammatory, and vasodilatory effects. Diabetes mellitus is a chronic disease that causes endothelial and platelet dysfunction leading to both microvascular and macrovascular complications. This mini-review highlights the emerging evidence suggesting benefits of using cilostazol in treating microvascular complications associated with diabetes mellitus.

METHODS

A review of literature was conducted using PubMed and Embase databases focusing on cilostazol use in diabetes mellitus.

RESULTS

Cilostazol demonstrated renoprotective effects in patients with diabetic nephropathy by reducing serum soluble adhesion molecule-1 and monocyte chemoattractant protein-1. Cilostazol's anti-inflammatory actions predictably attenuate glomerular damage from increased leukocyte adherence. Additionally, cilostazol delayed renal dysfunction secondary to type 2 diabetes mellitus as albuminuria was reduced most likely resulting from inhibition of nuclear factor kappa-induced inflammatory and endothelial markers. Cilostazol's anti-inflammatory actions in addition to its vasodilatory actions relieved retinal hypoxia and decreased excessive production of retinal blood vessels suggesting benefit in diabetic retinopathy. Cilostazol did not improve neuropathy symptom scores signifying that it may not be as beneficial in patients with diabetic peripheral neuropathy without diabetic nephropathy or diabetic retinopathy.

CONCLUSIONS

Cilostazol's pleiotropic effects may be beneficial in patients with type 2 diabetes mellitus and diabetic nephropathy. Additional, larger studies need to be conducted to assess the benefits and risks of using cilostazol as an alternative agent in treating patients with diabetic microvascular complications.