Nitrates

They release nitric oxide in vascular smooth muscle, which activates guanylyl cyclase and raises cyclic GMP; myosin light chains lose their phosphate and the muscle relaxes. Veins widen most, so blood pools and preload falls; arterioles and the large coronary arteries widen too. The heart needs less oxygen, which relieves angina.

• Glyceryl trinitrateUnlike isosorbide mononitrate, it acts within minutes under the tongue, so it can stop an attack as well as prevent one.
• Isosorbide mononitrateMost of the effect of isosorbide dinitrate comes from its conversion to this drug in the body.

• Relief of an angina attack
• Prevention of angina
• Heart failure in acute myocardial infarction (infusion)
• High blood pressure during surgery (infusion)

• Throbbing headacheKnown for
• Low blood pressure and faintingKnown forSerious
• Tolerance with continuous useKnown for
• Light-headedness on standing
• Flushing
• Reflex fast heart rate
• Paradoxical slow heart rate
• Nausea and vomiting
• Methemoglobinemia (rare)Serious
• Rash and contact dermatitis

What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.

• PDE-5 inhibitors such as sildenafil or tadalafil, and riociguat, are contraindicated: the combination can cause severe hypotension.
• Contraindicated in severe anemia, raised intracranial pressure and circulatory failure or shock.
• Tolerance develops with steady levels, so long-acting nitrates are dosed to leave a low-nitrate period each day.
• Hypertrophic obstructive cardiomyopathy, aortic or mitral stenosis or low blood volume make hypotension more likely.

Written for biofideX in plain words, after checking these references:

• Nitroglycerin sublingual tablets: label (DailyMed)
• Nitroglycerin in 5% dextrose injection: label (DailyMed)
• Isosorbide mononitrate extended-release tablets: label (DailyMed)
• Nitroglycerin (NCI Thesaurus)
• Isosorbide mononitrate tablets 20 mg: SmPC (emc)
• About glyceryl trinitrate (GTN) (NHS)

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.