Nitroglycerin

Nitroglycerin (also known as glyceryl trinitrate) is a medication from the nitrate class that is used to dilate blood vessels and reduce the strain on the heart. It is one of the most widely used drugs to relieve the symptoms of angina (chest pain) caused by ischemia (inadequate blood supply) to the heart muscle.

Nitroglycerin works by dilating blood vessels (including arteries) to increase blood flow to the heart and reduce its workload. It can also lower blood pressure, which is especially helpful for angina.

It is important to note that nitroglycerin should be taken only under the supervision of a doctor, as it can affect the heart rhythm and blood pressure. Dosage and frequency of use depend on the individual characteristics of the patient and the characteristics of his condition.

Indications Nitroglycerin

1. Angina(stable and unstable): Nitroglycerin is used to relieve symptoms of angina such as chest pain, caused by ischemia of the heart muscle. This can include stable angina (occurring with exercise and decreasing at rest) and unstable angina (occurring at rest or in response to minimal physical activity).
2. Acute angina pectoris and myocardial infarction: In cases of acute angina pectoris or myocardial infarction, nitroglycerin may be used to urgently relieve symptoms and improve blood supply to the heart muscle.
3. Heart Failure: Nitroglycerin may be used to reduce cardiac preload and improve blood supply to the heart muscle in patients with heart failure.
4. Hypertension: In rare cases, nitroglycerin may be used to lower blood pressure in hypertension.
5. Vascular catheterizations: Nitroglycerin may be used during vascular catheterization procedures to prevent or treat vasospasms and to facilitate the process.
6. Prevention of angina before exercise: Some patients may use nitroglycerin as a prophylactic before expected exercise to prevent angina.

Release form

1. Sublingual tablets: These tablets are placed under the tongue where they dissolve quickly, providing quick relief from angina symptoms.
2. Sublingual sprays: Nitroglycerin can be presented as sublingual sprays, which provide a similar rapid effect.
3. Patches: Transdermal vaporization systems can be used to gradually release nitroglycerin through the skin.
4. Injections: In some cases, nitroglycerin may be given as an injection into a vein for quick action in the event of an acute heart attack or heart failure.

Pharmacodynamics

1. Vascular smooth muscle relaxation: Nitroglycerin acts as a nitric oxide (NO) donor that stimulates the synthesis of cyclic guanosine monophosphate (cGMP) in vascular smooth muscle. This leads to relaxation of vascular walls and dilation of arteries and veins, which decreases vascular resistance and reduces cardiac preload.
2. Improve myocardial blood flow: Dilation of the coronary arteries by nitroglycerin increases blood flow in the myocardium (heart muscle), which may improve oxygen supply and reduce the risk of ischemia (lack of blood supply).
3. Decreased myocardial contractility: Some studies suggest that nitroglycerin may decrease myocardial contractility, which reduces the heart's need for oxygen and decreases its workload.
4. Peripheral vascular dilation: In addition, nitroglycerin can dilate peripheral blood vessels, which helps reduce vascular resistance and lower blood pressure.
5. Reducing cardiac preload: Venous dilation decreases venous return to the heart and reduces the volume of blood in the heart cavity, which reduces cardiac preload and decreases cardiac workload.

Pharmacokinetics

1. Absorption: Nitroglycerin can be absorbed through the skin, oral mucous membranes and hyoid space, and through the gastrointestinal tract when taken orally. It may also be administered intravenously or sublingually.
2. Distribution: Nitroglycerin is rapidly distributed in body tissues. It has high fat solubility and can penetrate the blood-brain barrier and the blood-placental barrier.
3. Metabolism: The main pathway of nitroglycerin metabolism is biotransformation in the liver to form active metabolites such as dinitroglycerin, mononitroglycerin and nitrohydrin. These metabolites have biological activity and may be involved in vasodilation.
4. Excretion: Nitroglycerin and its metabolites are eliminated from the body mainly by kidneys in the form of conjugates with glucuronic acid and with insignificant amount in unchanged form through urine.
5. Half-life: The half-life of nitroglycerin is only a few minutes due to its rapid metabolism and elimination from the body.
6. Mechanism of Action: Nitroglycerin dilates blood vessels (vasodilation), which leads to an increase in the lumen of arteries and veins, a decrease in vascular resistance and a decrease in cardiac preload. This reduces myocardial oxygen demand and improves blood flow to the heart.

Dosing and administration

The following are general guidelines for the use of different forms of nitroglycerin:

Sublingual tablets or spray

• For relief of angina pectoris: One 0.3-0.6 mg sublingual tablet or one spray under the tongue at onset of symptoms is usually recommended. If the attack persists, it may be repeated after 5 minutes, but no more than three doses within 15 minutes.
• Prevention of angina pectoris: The tablet or spray may be used 5-10 minutes before an anticipated exertion that could trigger an attack.

Transdermal patches

• Prevention of angina pectoris: The patch is applied to a clean, dry area of skin without hair and left in place usually for 12-14 hours, followed by a 10-12 hour break to avoid the development of tolerance to nitroglycerin.

Ointment

• Prevention of angina pectoris: Apply to the skin in an individually calculated dose, usually twice daily.

Intravenous injection

• In hospital settings: Dosage and rate of administration are individualized and should be monitored by medical personnel, especially when treating acute heart failure or monitoring blood pressure during surgery.

Important points when using nitroglycerin:

• To avoid the risk of serious low blood pressure, nitroglycerin should not be used in conjunction with erectile dysfunction medications such as sildenafil (Viagra), tadalafil (Sialis), and others.
• A common side effect of nitroglycerin is headache, which usually decreases with continued therapy.
• When using sublingual tablets or spray, it is important to sit or lie down to minimize the risk of fainting due to a drop in blood pressure.
• Always carry nitroglycerin if you have been diagnosed with angina and inform medical professionals in case of an emergency.

Use Nitroglycerin during pregnancy

The use of nitroglycerin during pregnancy is generally not recommended unless clearly needed and supervised by a doctor. Nitroglycerin is used to treat angina pectoris and other heart conditions caused by ischemia (insufficient blood supply to the heart muscle). There are not enough studies to determine its safety for use during pregnancy.

In individual cases where the benefits of nitroglycerin for the mother outweigh the potential risks to the fetus, a doctor may prescribe nitroglycerin to a pregnant woman. However, this should be done under the strict supervision of a doctor who will assess the benefits and risks.

Nitroglycerin is usually used to relieve angina attacks or to prevent them from occurring. During pregnancy, your doctor may consider alternative treatments or management that may be safer for the mother and fetus.

Contraindications

1. Hypotension: Nitroglycerin may cause a decrease in blood pressure (hypotension), therefore its use may be contraindicated in patients with low blood pressure.
2. Hypersensitivity: People with known hypersensitivity to nitroglycerin or other nitrates should not use this drug because of the risk of allergic reactions.
3. Hypertrophic obstructive cardiomyopathy: In this condition, the use of nitroglycerin may worsen obstruction of the left ventricular outflow tract of the heart and lead to worsening of symptoms.
4. Pericarditis: Use of nitroglycerin in acute pericarditis may increase cardiac compression and worsen the clinical condition.
5. Severe anemia: Nitroglycerin may increase hypoxia in patients with severe anemia, therefore its use may be contraindicated in such cases.
6. Myocardial hypertrophy: In patients with myocardial hypertrophy of the left ventricular myocardium of the heart, nitroglycerin may worsen cardiac function and cause exacerbation of symptoms.
7. Iron deficiency anemia: In patients with iron deficiency anemia, the use of nitroglycerin may increase symptoms of hypoxia and exacerbate the clinical picture.
8. Hyperglycemia: Nitroglycerin can cause an increase in blood glucose levels, which can be problematic for diabetic patients.
9. Pregnancy and breastfeeding: The safety of nitroglycerin use during pregnancy and breastfeeding has not been established; therefore, its use should be evaluated and recommended by a physician.

Side effects Nitroglycerin

1. Headache: One of the most common side effects caused by dilatation of blood vessels in the brain. Headaches can range from mild to severe, but usually decrease over time with continued treatment.
2. Reddening of the skin (flushes): A feeling of warmth and visible redness of the skin on the face and upper body, also resulting from dilation of blood vessels.
3. Lowering of blood pressure (hypotension): Nitroglycerin may cause a sharp drop in blood pressure, which may lead to dizziness, weakness and even fainting, especially when getting up from a lying or sitting position.
4. Palpitations (tachycardia): In some cases, nitroglycerin may cause palpitations as a reflex response to lower blood pressure.
5. Nausea and vomiting: Although less common, some people may experience nausea and even vomiting after taking nitroglycerin.
6. Syncope: Due to decreased blood pressure, fainting may occur, especially if the patient gets up from a seat quickly.
7. Fatigue and weakness: Some people may feel tired or generally weak after taking nitroglycerin.
8. Dizziness: Side effect associated with decreased blood pressure and vasodilation.

Overdose

1. Severe dizziness and fainting: As a result of vasodilation and decreased blood pressure, hypotension may develop, leading to dizziness and even loss of consciousness.
2. Heart palpitations or arrhythmias: An overdose of nitroglycerin may cause palpitations or heart rhythm disturbances.
3. Headache: Severe headache, migraine or a feeling of heaviness in the head may occur against the background of vascular dilation.
4. Skin pallor: As a result of dilated peripheral blood vessels, the skin may become pale and cold to the touch.
5. Digestive disorders: Nausea, vomiting and other digestive disorders may occur.

Interactions with other drugs

1. Blood pressure-lowering drugs (antihypertensive drugs): Nitroglycerin may increase the hypotensive effect of other antihypertensive drugs such as beta-blockers, ACE inhibitors, calcium antagonists and diuretics. This may lead to a strong decrease in blood pressure and the occurrence of orthostatic hypotension.
2. Drugs for the treatment of erectile dysfunction: Co-administration of nitroglycerin with phosphodiesterase type 5 inhibitors (e.g., sildenafil, tadalafil, or vardenafil) used to treat erectile dysfunction may cause an extreme drop in blood pressure and the development of serious complications.
3. Drugs for the treatment of pulmonary artery hypertension (cor pulmonale hypertension): Nitroglycerin is not recommended for concomitant use with drugs for the treatment of pulmonary hypertension, such as sildenafil (Revatio) or tadalafil (Adcirca), as this may cause a severe decrease in blood pressure.
4. Preparations containing alcohol: Alcohol consumption together with nitroglycerin may enhance its hypotensive effect and increase the risk of orthostatic hypotension.
5. Blood clotting-enhancing drugs: Nitroglycerin may increase the effect of anticoagulants (e.g. Warfarin or heparin) and antiaggregants (e.g. Acetylsalicylic acid), which may increase the risk of bleeding.
6. Drugs increasing hypotensive effect: Nitroglycerin may increase the hypotensive effect of alpha-adrenoblockers, aminitradil and other drugs, which may lead to a significant decrease in blood pressure.

Storage conditions

1. Temperature: Normally, nitroglycerin should be stored at room temperature between 15 and 30 degrees Celsius (59-86 degrees Fahrenheit).
2. Dryness: Store nitroglycerin in a dry place to avoid moisture, which can adversely affect the quality of the drug.
3. Light: Nitroglycerin should be stored in a dark place protected from direct sunlight. Light may cause decomposition of the drug.
4. Packaging: Store nitroglycerin in the original package or container to prevent air and moisture.
5. Children: Make sure nitroglycerin is stored out of reach of children to avoid accidental use.
6. Special conditions: In some cases, there may be additional storage recommendations on the package or in the drug instructions. Please refer to these recommendations for more precise information.