Adempas is Bayer’s novel formulation aimed at treating patients with pulmonary hypertension (PH). Chemically known as riociguat, the drug is the first of a novel class of stimulators of soluble guanylate cyclase (sGC), an enzyme responsible for vasodilation and lowering of blood pressure, and the only receptor of nitric oxide in the body.
Patients who suffer from two main categories of PH, chronic thromboembolic pulmonary hypertension (CTEPH, WHO Group 4, where vasoconstriction persists even after surgical intervention or cases where surgery is not possible), or pulmonary arterial hypertension (PAH, WHO Group 1) are prescribed Adempas by specialists to improve exercise capacity and WHO functional class, as well as cause a delay or complete halt in clinical worsening.
How Adempas (riociguat) Works
Adempas is an oral formulation. Chemically, riociguat is methyl 4,6-diamino-2-[1-(2-fluorobenzyl)-1Hpyrazolo [3,4-b]pyridin-3-yl]-5-pyrimidinyl (methyl) carbamate, available as white to yellowish, round coated tablets. Nitric oxide (NO) acts as a stimulator for vasodilation. In patients with PH, arteries become constricted beyond normal limits, which is why the blood pressure rises exponentially. In such cases, NO synthase, responsible for production of NO, is secreted in lower levels, which reduces the amount of NO available.
In addition to vasodilation, nitric oxide also reduces pulmonary smooth muscle cell growth and acts against platelet inhibition, two main factors behind PAH pathogenesis. In such cases, riociguat, which is a NO-independent sGC stimulator, balances the nitric-oxide-soluble guanylate cyclase-cyclic guanosine monophosphate (NO-sGC-cGMP) pathway, resulting in activation of cGMP-dependent protein kinase (protein kinase G), regulating the calcium ion concentration in the cytosol. This improves actin-myosin contractility that results in improved vasodilation.
Clinical Trials for Adempas (riociguat)
After a series of successful clinical trials over a period of years — the most notable ones being the Chronic Thromboembolic Pulmonary Hypertension sGC-Stimulator Trial (CHEST) and the Pulmonary Arterial Hypertension sGC-Stimulator Trial (PATENT) (results published in the July 25, 2013 issue of the New England Journal of Medicine) — Bayer received approval for Adempas to be recommended for treating both CTEPH and PAH in October 2013.
Adempas (riociguat) Dosing
Dosing may vary according to the severity of the condition. The normal range of medication is 0.5 to 2.5 mg (0.5, 1.0, 1.5, 2.0, 2.5 mg) three times a day. Those who are taking the medicine should not be taking antacids within an hour of the dose. Patients with other conditions like heart disease, kidney, or liver disease (especially if on dialysis), pulmonary veno-occlusive disease (PVOD), cases of pulmonary bleeding or coughing with blood, low blood pressure or circulation problems, should consider special advice before consuming Adempas.
Pregnant women are advised not to take the drug. Patients who intend to use drugs like dipyridamole, theophylline, drugs for erectile dysfunction, or nitrite-based drugs for chest pain, need to consult their doctors for dosing details and modifications. Most common side effects associated with the drug include mild dizziness, weakness, headache, nausea, vomiting, diarrhea, and swelling of limbs.
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