What Factors Affect a Sufficient Nifedipine Dose?

The main ingredient of this product is nifedipine.
Chemical name: 2,6-dimethyl-4 (2-nitrophenyl) -1,4-dihydro-3,5-pyridinedicarboxylic acid dimethyl chemical structural formula:

Nifedipine tablets, the indications are 1. Angina pectoris: variant angina pectoris; unstable angina pectoris; chronic stable angina pectoris. 2. Hypertension (alone or in combination with other antihypertensive drugs).

Drug Name

Nifedipine tablets

Drug type

Prescription medicines, essential medicines, medicines for medical workers' injuries

Use classification

Selective calcium antagonist

Nifedipine tablets ingredients

The main ingredient of this product is nifedipine.
Chemical name: 2,6-dimethyl-4 (2-nitrophenyl) -1,4-dihydro-3,5-pyridinedicarboxylic acid dimethyl chemical structural formula:

Molecular formula: C ₁₇ H ₁₈ N ₂ O ₆
Molecular weight: 346.34

Nifedipine Tablet Properties

This product is a sugar-coated tablet, which is yellow after removing the coating.

Nifedipine tablets indications

1. Angina pectoris: variant angina pectoris; unstable angina pectoris; chronic stable angina pectoris.
2. Hypertension (alone or in combination with other antihypertensive drugs).

Nifedipine tablets specifications

10mg

Nifedipine tablets dosage

1. The dose of nifedipine should be adjusted gradually depending on the patient's tolerance and control of angina pectoris. Overdose of nifedipine can cause hypotension.
2. Starting from a small dose, the general starting dose is 10 mg / time (one tablet at a time), orally 3 times a day; the usual maintenance dose is 10-20 mg / time (1-2 tablets at a time), three times a day. Some patients with significant coronary spasm can be used up to 20-30mg / time (2-3 tablets at a time), 3-4 times a day. The maximum dose should not exceed 120mg / day (12 tablets per day). If the condition is urgent, you can chew or take 10mg / time under the tongue (one tablet at a time), and decide to re-administer the medicine according to the patient's response to the drug.
3 It usually takes 7-14 days to adjust the dose. If the patient's symptoms are obvious and the condition is urgent, the dose adjustment period can be shortened. Depending on the patient's response to the drug, the frequency of attacks and the dose of nitroglycerin under the tongue, the amount of nifedipine can be adjusted from 10-20 mg (1 tablet-2 tablets) to 30 mg / time (3 tablets at a time) within 3 days ), 3 times a day.
4 In-patients under strict monitoring can be increased by 10 mg (1 tablet) every 4-6 hours according to the control of angina pectoris or ischemic arrhythmia.

Adverse reactions of nifedipine tablets

1. Peripheral edema is common after taking the medication (peripheral edema is dose-related, with a 4% incidence at 60 mg / day and 12.5% at 120 mg / day); dizziness; headache; nausea; fatigue and facial flushing (10%). Transient hypotension (5%), no need to stop medication (transient hypotension is dose-related, the incidence rate is [2% at 60mg / day, and 5% at 120mg / day] . Angina pectoris in some patients may be related to hypotension. Palpitations, nasal congestion, chest tightness, shortness of breath, constipation, diarrhea, gastrointestinal cramps, abdominal distension, skeletal muscle inflammation, joint stiffness, muscle cramps, nervousness, tremors, nervousness, sleep disturbances, blurred vision, imbalance, etc. (2% ). Syncope (0.5%), reduction or co-administration with other antianginal medications no longer occur.
2. Rare anemia; leukopenia; thrombocytopenia; purpura; allergic hepatitis; gingival hyperplasia; depression; paranoia; instant blindness at peak blood 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 People who are allergic to this product may develop allergic hepatitis, rash, and even exfoliative dermatitis.

Nifedipine tablets contraindications

Allergic to nifedipine is prohibited.

Notes for nifedipine tablets

1. Hypotension Most patients have only mild hypotension after taking nifedipine, and some patients have severe hypotension symptoms. This response often occurs during dose adjustments or additions, especially when combined with beta-blockers. Monitor your blood pressure during this period, especially when combined with other antihypertensive drugs.
2. Fentanyl anesthesia patients undergoing coronary artery bypass grafting (or other surgery), taking nifedipine alone or in combination with -blockers can cause severe hypotension, at least 36 should be discontinued if conditions permit hour.
3 Very few patients with angina pectoris and / or myocardial infarction, especially those with severe coronary artery stenosis, have reflex sympathetic excitement after hypotension and increased heart rate during taking nifedipine or increasing doses, and the incidence of angina pectoris or myocardial infarction increases.
4 Peripheral edema occurs in 10% of patients with mild to moderate peripheral edema, which is related to arterial dilatation. Edema mostly occurs in the lower extremities 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. Beta-blocker "bounce" symptoms Suddenly discontinuing beta-blocker and using nifedipine may even worsen angina pectoris. The former must be gradually reduced.
6. Congestive heart failure. A few patients receiving beta-blockers can start heart failure after taking nifedipine, and patients with severe aortic stenosis are at greater risk.
7. Interference in diagnosis When using this product, there may be elevated alkaline phosphatase, creatine phosphokinase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase. Generally there are no clinical symptoms, but Cholestasis and jaundice reported; decreased platelet aggregation and prolonged bleeding time; direct Coomb test with / without hemolytic anemia
8. Patients with liver and kidney dysfunction who are taking beta-blockers should be used with caution, and it is advisable to start with small doses to prevent the induction or exacerbation of hypotension and increase the incidence of angina pectoris, heart failure, and even myocardial infarction. Patients with chronic renal failure occasionally have reversible elevated blood urea nitrogen and creatinine, and the relationship with nifedipine is not clear.
9. Suspension should not be stopped for long-term administration, in order to avoid the phenomenon of rebound syndrome due to withdrawal syndrome.

Nifedipine tablets for pregnant and lactating women

1. No detailed clinical research data. Clinically, nifedipine is used in pregnant women with hypertension.
2. Nifedipine can be secreted into breast milk, and breastfeeding women should stop taking medicine or stop breastfeeding.

Nifedipine tablets for children

still uncertain.

Nifedipine tablets for the elderly

The half-life of nifedipine is prolonged in the elderly. Pay attention to adjusting the dose when applying.

Nifedipine tablets drug interactions

1. Nitrate is used in combination with this product to control the onset of angina pectoris and is well tolerated.
2. Beta-blockers are most well tolerated and effective in combination with this product, but individual patients may induce and exacerbate hypotension, heart failure and angina.
3 Digitalis may increase blood digoxin concentration, suggesting that the blood concentration of digoxin should be monitored when first using, adjusting the dose or discontinuing this product.
4 Drugs with a high protein binding rate, such as biscoumarins, phenytoin, quinidine, quinine, warfarin, etc., are used together with this product, the free concentration of these drugs often changes.
5. The peak plasma concentration of cimetidine increases with this product. Pay attention to adjust the dose.

Nifedipine tablets overdose

There is not enough research data. Existing literature shows that increasing the dose can cause excessive expansion of peripheral blood vessels, leading to or exacerbating hypotension. Patients with clinically low blood pressure due to drug overdose should be given cardiovascular support treatment in a timely manner, including cardiopulmonary monitoring, lower extremity elevation, attention to circulating blood volume, and urine output. If there are no contraindications, vasoconstrictors (norepinephrine) can be used to restore vascular tone and blood pressure. Patients with liver dysfunction have longer drug clearance. Hemodialysis cannot clear nifedipine.

Pharmacology and Toxicology of Nifedipine Tablets

Nifedipine is a dihydropyridine calcium antagonist, which can selectively inhibit the transmembrane transport of calcium ions into cardiomyocytes and smooth muscle cells, and inhibit the release of calcium ions from cells without changing the plasma calcium ion concentration.
Pharmacology (1) This product can relax coronary arteries in normal blood supply area and ischemic area, antagonize spontaneous or ergometrine-induced coronary spasm, increase myocardial oxygen delivery in patients with coronary spasm, relieve and prevent coronary spasm.
(2) This product can inhibit myocardial contraction, reduce myocardial metabolism, and reduce myocardial oxygen consumption.
(3) This product can relax peripheral resistance blood vessels, reduce peripheral resistance, reduce systolic blood pressure and diastolic blood pressure, and reduce cardiac afterload.
(4) This product can delay sinoatrial node function and atrioventricular conduction in isolated hearts; overall animal and human electrophysiological studies have not found that this product can delay atrioventricular conduction, prolong sinus node recovery time, and slow sinoatrial node The role of rate.
3. Carcinogenic, mutagenic and reproductive toxicity have no carcinogenic effect. No mutagenicity. Large-dose application can reduce female rats' fertility; can cause teratogenicity; can cause miscarriage (increased drug absorption in fetal rats, increased mortality in fetal rats, and decreased survival in newborns). Pregnant monkeys taking 2 / 3-2 times the maximum human dose can cause small placenta and villous hypoplasia; giving rats 3 times the maximum human dose can cause prolonged pregnancy. The effect on human fertility is unknown.

Pharmacokinetics of nifedipine tablets

It is absorbed quickly and completely after oral administration. The blood drug concentration can be measured 10 minutes after oral administration, and the peak blood drug concentration is reached after about 30 minutes. The peak time of chewing or sublingual administration is earlier. There was no significant difference in bioavailability and half-life between nifedipine between 10-30mg. There was basically no difference in relative bioavailability when swallowed, chewed or nifedipine tablets were taken under the tongue. Nifedipine is highly bound to plasma proteins, about 90%. The effect takes 15 minutes orally, and the effect reaches a peak in 1-2 hours, and the effect lasts for 4-8 hours; sublingual administration takes effect in 2-3 minutes, and reaches a peak in 20 minutes. T _1/2 is biphasic, T _{1 / 2} is 2.5-3 hours, and T _{1 / 2} is 5 hours. The drug is converted into inactive metabolites in the liver, about 80% of which is excreted by the kidneys and 20% is excreted in the feces. Patients with liver and kidney dysfunction have reduced nifedipine metabolism and excretion rates.

Storage of nifedipine tablets

Shading and sealed

Nifedipine tablets packaging

Plastic bottle, 100 tablets / bottle

Validity of nifedipine tablets

24 months

Executive standard for nifedipine tablets

"Chinese Pharmacopoeia" 2010 edition two