Nicorandil

Nicorandil

Systematic (IUPAC) name
2-[(pyridin-3-ylcarbonyl)amino]ethyl nitrate
Clinical data
AHFS/Drugs.com	International Drug Names
Pregnancy category	AU: B3
Legal status	UK: POM (Prescription only)
Routes of administration	Oral
Pharmacokinetic data
Bioavailability	75 to 80%
Protein binding	25%
Metabolism	Hepatic
Biological half-life	1 hour
Excretion	Renal (21%)
Identifiers
CAS Number	65141-46-0 Y
ATC code	C01DX16 (WHO)
PubChem	CID: 47528
IUPHAR/BPS	2411
ChemSpider	43240 Y
UNII	260456HAM0 Y
KEGG	D01810 Y
ChEBI	CHEBI:31905 N
ChEMBL	CHEMBL284906 Y
Chemical data
Formula	C8H9N3O4
Molecular mass	211.175 g/mol
SMILES O=C(NCCO[N+]([O-])=O)c1cccnc1
InChI InChI=1S/C8H9N3O4/c12-8(7-2-1-3-9-6-7)10-4-5-15-11(13)14/h1-3,6H,4-5H2,(H,10,12) Y Key:LBHIOVVIQHSOQN-UHFFFAOYSA-N Y
NY (what is this?)  (verify)

Nicorandil is a vasodilatory drug used to treat angina. It is marketed under the trade names Ikorel (in the United Kingdom, Australia and most of Europe), Angedil (in Romania, Poland), Dancor (in Switzerland), Nikoran,PCA (in India), Aprior (in the Philippines), Nitorubin (in Japan), and Sigmart (in Japan, South Korea and Taiwan). Nicorandil is not available in the United States.

Angina is chest pain that results from episodes of transient myocardial ischemia. This can be caused by diseases such as atherosclerosis, coronary artery disease and aortic stenosis. Angina commonly arises from vasospasm of the coronary arteries. There are multiple mechanisms causing the increased smooth muscle contraction involved in coronary vasospasm, including increased Rho-kinase activity. Increased levels of Rho-kinase inhibit myosin phosphatase activity, leading to increased calcium sensitivity and hypercontraction. Rho-kinase also decreases nitric oxide synthase activity, which reduces nitric oxide concentrations. Lower levels of nitric oxide are present in spastic coronary arteries. L-type calcium channel expression increases in spastic vascular smooth muscle cells, which could result in excessive calcium influx, and hypercontraction.

Nicorandil is an anti-angina medication that has the dual properties of a nitrate and K+ATP channel agonist. In humans, the nitrate action of nicorandil dilates the large coronary arteries at low plasma concentrations. At high plasma concentrations nicorandil reduces coronary vascular resistance, which is associated with increased K+ATP channel opening.

Mechanism of action

Nitrate: Nicorandil stimulates guanylate cyclase to increase formation of cyclic GMP (cGMP). cGMP activates protein kinase G (PKG) which phosphorylates and inhibits GTPase RhoA and decreases Rho-kinase activity. Reduced Rho-kinase activity permits an increase in myosin phosphatase activity, decreasing the calcium sensitivity of the smooth muscle.

PKG also activates the sarcolemma calcium pump to remove activating calcium. PKG acts on K+ channels to promote K+ efflux and the ensuing hyperpolarization inhibits voltage-gated calcium channels. Overall, this leads to relaxation of the smooth muscle and coronary vasodilation.

The effect of nicorandil as a vasodilator is mainly attributed to its nitrate property. Yet, nicorandil is effective in cases where nitrates, such as nitroglycerine, are not effective. Studies show that this is due to its K+ATP channel agonist action which causes pharmacological preconditioning and provides cardioprotective effects against ischemia. Nicorandil activates K+ATP channels in the mitochondria of the myocardium, which appears to relay the cardioprotective effects, although the mechanism is still unclear.

Side effects

Side effects listed in the British National Formulary include flushing, palpitations, weakness and vomiting. More recently, perianal, ileal and peristomal ulceration has been reported as a side effect. Anal ulceration is now included in the British National Formulary as a reported side effect. Other side effects include severe toothache, and nasal congestion.

See also

• Nitrovasodilator

References

• Dr.Hosny Mohaed, Brief ACSs.