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Source: Thailand Medical News  Dec 13, 2019  4 years, 2 months, 1 week, 5 days, 51 minutes ago

Dofetilide, An Antiarrhythmic Drug Identified As Candidate For Drug Repurposing To Treat Pulmonary Arterial Hypertension

Dofetilide, An Antiarrhythmic Drug Identified As Candidate For Drug Repurposing To Treat Pulmonary Arterial Hypertension
Source: Thailand Medical News  Dec 13, 2019  4 years, 2 months, 1 week, 5 days, 51 minutes ago
Pulmonary arterial hypertension (PAH),which is basically  high blood pressure in the lungs,  is a potentially fatal disease caused by obstruction of blood flow in the lungs. A new study in The American Journal of Pathology sheds light on the pathology underlying PAH and shows that dofetilide, an FDA-approved KV11.1 channel blocker for the treatment of cardiac arrhythmias (brand name: Tikosyn), may be used for treatment of Pulmonary arterial hypertension.

Typically, Kv11.1 potassium selective channels are recognized for their function in the heart. Despite the importance of Kv11.1 channels for many physiological processes, their expression and function in pulmonary vasculature and potential role in Pulmonary arterial hypertension  and chronic obstructive pulmonary disease (COPD associated vascular remodeling had not been investigated.

Researchers  examined lung tissue from patients with COPD and rats with experimentally-induced Pulmonary arterial hypertension.

Dr Tinatin I. Brelidze, Ph.D., assistant professor of pharmacology in the Department of Pharmacology and Physiology at Georgetown University Medical Center, Washington, DC, USA told Thailand Medical News, "Our study suggests that Kv11.1 channel blockers may have therapeutic potential for treatment of PAH. Specifically, we have shown that dofetilide, which is already FDA-approved as an antiarrhythmic and therefore has passed all of the drug safety requirements, can be considered for repurposing for treatment of patients with Pulmonary arterial hypertension."

The medical investigators observed that Kv11.1 potassium selective channels are expressed in lungs and blocking these channels with dofetilide inhibits Pulmonary arterial hypertension  associated with vascular remodeling. In control rats, Kv11.1 channels were expressed in the smooth muscle cell (SMC) layer of large diameter pulmonary arteries (PAs), but not in the SMCs of small diameter PAs (less than 100 μm). In rats with experimentally-induced PAH, the expression of Kv11.1 channels increased and the channels were found in both small and large PAs. The PA walls thickened as they became more muscular, and the lumens shrank.

As rats with Pulmonary arterial hypertension  were treated with dofetilide, there was no evidence of the typical pathological changes in the vasculature associated with PAH. Dofetilide increased lumen diameter and decreased PA wall thickness to levels seen in the control rats without Pulmonary arterial hypertension.

In the case of healthy human lung tissue, Kv11.1 channels were present only in the walls of large-diameter PAs. Lung tissue from patients with COPD showed collapse of alveoli, mild edema of the arterial walls, and fibrosis and t hickening of PA walls. Kv11.1 channels were found in the walls of both large and small PAs, similar to that reported in rats with Pulmonary arterial hypertension.

Basically, Kv11.1 potassium channels are voltage-activated potassium channels that are expressed in many tissues and organs of the body. In the heart, Kv11.1 potassium channels help to repolarize cardiac action potentials to maintain proper heart rhythm whereas, in the brain, Kv11.1 channels regulate neuronal excitability. Inhibition of Kv11.1 channels also likely decreases the proliferation of cancer cells. "We hypothesize that similar to cancer, enlargement of SMCs in Pulmonary arterial hypertension  is associated with the overexpression of Kv11.1 channels," noted Dr. Brelidze.

As there is already extensive clinical experience with dofetilide for cardiac arrhythmias and it has passed all drug safety requirements, the investigators suggest it merits consideration as a potential treatment for patients with Pulmonary arterial hypertension.

Reference : "Increased Smooth Muscle Kv11.1 Channel Expression in Pulmonary Hypertension and Protective Role of Kv11.1 Channel Blocker Dofetilide," American Journal of Pathology (2019). DOI: 10.1016/j.ajpath.2019.09.010


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