Nifedipine Tablets

Nifedipine Tablets. Synonyms: Adalat, Procardia, etc.The indications are as follows:1.Angina pectoris: variant angina pectoris; unstable angina pectoris; chronic stable angina pectoris.2.

Hypertension (used alone or in combination with other antihypertensive drugs).

【Drug Name】
Generic name: Nifedipine Tablets
English name: Nifedipine Tablets
【Ingredients】Nifedipine
Chemical name: 2,6-dimethyl-4 (2-nitrophenyl) -1,4-dihydro-3,5-pyridinedicarboxylic acid dimethyl ester
Molecular formula: C17H18N2O6
Molecular weight: 346.34
【Appearance】A film coated tablet, which appears yellow after removing the coating.
【Indications】1. Angina pectoris: variant angina pectoris; Unstable angina pectoris; Chronic stable angina.
2. Hypertension (alone or in combination with other antihypertensive drugs).
【Specification】5mg.

【Usage and dosage】
1. The dosage of nifedipine should be gradually adjusted according to the patient's tolerance and control of angina pectoris. Overdosing of nifedipine can lead to low blood pressure.
2. Start taking from a small dose, usually starting at 10mg/time (2 tablets per time), orally taken 3 times a day; The commonly used maintenance dose is 10-20mg/time orally (2-4 tablets per time), 3 times a day. For patients with obvious coronary spasm, it can be used up to 20-30mg/time (4-6 tablets per time), 3-4 times a day. The maximum dose should not exceed 120mg/day (24 tablets per day). If the condition is urgent, it can be chewed and taken orally or sublingually at a dose of 10mg/time (2 tablets per time). Depending on the patient's response to the medication, it can be decided to administer it again.
3. Usually, adjusting the dosage takes 7-14 days. If the patient's symptoms are obvious and the condition is urgent, the dose adjustment period can be shortened. Based on the patient's response to medication, frequency of attacks, and dosage of sublingual nitroglycerin, the dosage of nifedipine can be adjusted from 10-20mg (2-4 tablets) to 30mg/time (6 tablets at a time) within 3 days, 3 times a day.
4. For hospitalized patients under strict monitoring, 10mg (2 tablets) can be added every 4-6 hours based on the control of angina or ischemic arrhythmia.
【Adverse reactions】

1. Common occurrence of peripheral edema after medication (peripheral edema is dose-dependent, with an incidence rate of 4% when taking 60mg/day and 12.5% when taking 120mg/day); dizzy, headache, disgusting, fatigue and facial flushing (10%). Transient hypotension (5%), often does not require discontinuation of medicine (transient hypotension is dose-dependent, with an incidence of 2% at a dose of 60mg/day and 5% at a dose of 120mg/day). Individual patients may experience angina, which may be related to hypotensive reactions. Palpitations, nasal congestion, chest tightness, shortness of breath, constipation, diarrhea, gastrointestinal spasm, abdominal distention, inflammation of skeletal muscles, joint stiffness, muscle spasms, mental tension, tremble, neuroticism, sleep disorders, blurred vision and imbalance, etc. (2%) can also be seen. Fainting (0.5%) , will no longer occur if reduced or combined with other anti angina drugs.
2. Rare anemia, decreased white blood cells, thrombocytopenia, purpura, allergic hepatitis, gingival hyperplasia, depression, paranoia, instantly blind at the peak of blood drug concentration, erythematous limb pain, antinuclear antibody positive arthritis, etc. (0.5%).
3. Possible serious adverse reactions: The incidence of myocardial infarction and congestive heart failure is 4%; The incidence of pulmonary edema is 2%; The incidence of arrhythmia and conduction block is less than 0.5% each.
4. Allergens to this product may develop allergic hepatitis, rash, and even exfoliative dermatitis.
【Contraindication】It is contraindicated for individuals allergic to nifedipine.

【Precautions】
1.Hypotension: Most patients with low blood pressure only experience mild hypotension after taking nifedipine, and a few patients may experience severe hypotension symptoms. This reaction often occurs during dose adjustment or dosage increase, especially when combined with beta blockers. During this period, blood pressure needs to be monitored, especially when combined with other antihypertensive drugs.
2.Patients undergoing coronary artery bypass grafting (or other surgeries) under fentanyl anesthesia may experience severe hypotension when taking nifedipine alone or in combination with beta blockers. If conditions permit, the medication should be discontinued for at least 36 hours.
3.Angina and/or myocardial infarction: A very small number of patients, especially those with severe coronary artery stenosis, experience reflex arousal and increased heart rate after taking nifedipine or increasing doses, leading to an increased incidence of angina or myocardial infarction.
4.Peripheral edema: 10% of patients experience mild to moderate peripheral edema, which is related to arterial dilation. Edema often first occurs in the lower limbs and can be treated with diuretics. For patients with congestive heart failure, it is necessary to distinguish whether edema is caused by further deterioration of left ventricular function.
5.Symptoms of "rebound" of beta blockers: Sudden discontinuation of beta blockers and use of nifedipine, may occasionally result in angina pectoris. The dosage of the former should be gradually reduced.
6.Congestive heart failure: A small number of patients who receive beta blockers may develop heart failure after starting to take nifedipine, and patients with severe aortic stenosis are at a greater risk.
7.Interference with diagnosis: Using this product, may occasionally increase in alkaline phosphatase, creatine phosphokinase, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase. Generally, there are no clinical symptoms, but there have been reported that bile stasis and jaundice; decreased platelet aggregation and prolonged bleeding time; direct Coomb test positive with/without hemolytic anemia.
8.Patients with liver and kidney dysfunction: patients who are taking beta blockers should be cautious and start with small doses to prevent inducing or worsening hypotension, increasing the incidence of angina, heart failure, and even myocardial infarction. Patients with chronic renal failure may occasionally experience reversible increases in blood urea nitrogen and creatinine when using this product, and the relationship with nifedipine is not clear enough.
9.Long term administration should not be sudden arrested to avoid the occurrence of withdrawal syndrome and rebound.
【Pregnant and lactating women】
1. There is no detailed clinical research data. Animal experiments have shown that nifedipine has a teratogenic effect on embryos, but there is no relevant human report yet.
2. Nifedipine can be secreted into breast milk. Breast-feeding women should either stop taking the drug or stop breast-feeding.
【Children】 Not clear.
【Elderly Patients】 The half-life of nifedipine is prolonged in the elderly, so attention should be paid to adjusting the dosage during its application.
【Drug Interactions】
1.Nitrates: When combined with this product, it can control the onset of angina pectoris and has good tolerance.
2.β-blockers: The combination of this product with β-blockers is well - tolerated and effective in the vast majority of patients. However, in some individual patients, it may induce and exacerbate hypotension, heart failure, and angina pectoris.
3.Digitalis: This product may increase the blood digoxin concentration. It is recommended to monitor the blood digoxin concentration when initially using, adjusting the dosage, or monitored the blood concentration of digoxin when discontinuing this product.
4.When used the drugs with high protein - binding rates, such as Coumarin anticoagulants, Phenytoin sodium, Quinidine, Quinine, Warfarin, etc., the free concentrations of these drugs often change.
5.When cimetidine is used together with this product, the plasma peak concentration of this product increases. Attention should be paid to adjusting the dosage.
6. Patients undergoing coronary artery bypass grafting (or other surgeries) under fentanyl anesthesia may experience severe hypotension when taking nifedipine alone or in combination with beta blockers. If conditions permit, the medication should be discontinued for at least 36 hours.
【Pharmacology and toxicology】Nifedipine is a dihydropyridine calcium antagonist. It can selectively inhibit the transmembrane transport of calcium ions into myocardial cells and smooth muscle cells and inhibit the release of calcium ions from the cells without changing the plasma calcium ion concentration.
1. Pharmacology
(1) This product can simultaneously dilate the coronary arteries in both the normal blood - supply area and the ischemic area, antagonize spontaneous or ergotamine - induced coronary artery spasm, increase the delivery of myocardial oxygen in patients with coronary artery spasm, and relieve and prevent coronary artery spasm.
(2) This product can inhibit myocardial contraction, reduce myocardial metabolism, and decrease myocardial oxygen consumption.
(3) This product can dilate the peripheral resistance vessels, reduce peripheral resistance, reduce both systolic and diastolic blood pressure, and relieve the after - load of the heart.
(4) This product can delay the function of the sino - atrial node and atrioventricular conduction of the isolated heart; electrophysiological studies in intact animals and humans have not found that this product has the effect of delaying atrioventricular conduction, prolonging the sino - atrial node recovery time and slowing the sino - atrial node rate.
2. Toxicology
There is no carcinogenic effect. There is no mutagenicity. High - dose application can reduce the fecundity of female mice; it can cause teratogenesis; it can cause abortion (the drug absorption rate of fetal mice increases, the mortality rate of fetal mice rises, and the survival rate of newborn mice decreases). Pregnant monkeys taking 2/3 - 2 times the maximum human dose can lead to small placentas and incomplete villus development; giving rats 3 times the maximum human dose can cause pregnancy prolongation. The impact on human fecundity is still unclear.

【Pharmacokinetics】
It is rapidly and completely absorbed after oral administration. Its blood drug concentration can be detected 10 minutes after oral administration, and the peak blood drug concentration is reached approximately 30 minutes later. The time to reach the peak is advanced when the drug is chewed or sublingually administered. There is no significant difference in bioavailability and half - life when the dose of nifedipine is between 10 - 30mg. There is basically no difference in relative bioavailability among swallowing, chewing, and sublingual administration of nifedipine tablets. Nifedipine is highly bound to plasma proteins, approximately 90%. It takes effect 15 minutes after oral administration, reaches its peak effect in 1 - 2 hours, and the effect lasts for 4 - 8 hours; it takes effect 2 - 3 minutes after sublingual administration and reaches the peak in 20 minutes. The T1/2 is biphasic, with T1/2α being 2.5 - 3 hours and T1/2β being 5 hours. The drug is converted into inactive metabolites in the liver, and approximately 80% is excreted through the kidneys and 20% is excreted with feces. The metabolism and excretion rate of nifedipine is reduced in patients with liver and kidney insufficiency.
【Storage】Protect from light and store in a sealed container.
【Package】Oral solid drug, packed in high-density polyethylene bottle, 100 tablets per bottle.
【Validity】36 months.
【Standard】Ch.P. 2020, Part II.
【Drug approval number】Guoyao Zhunzi H12020305