Nifecaine

Uses

Nifedipine is used for the management of all types of essential & renal hypertension. Also used for the management of hypertension during pregnancy & during coronary by pass surgery.

Nifedipine is also used for prophylaxis and the treatment of unstable & variant angina, myocardial infarction, and silent myocardial ischaemia. Moreover Nifedipine is also used in Raynaud's phenomenon & heart failure.

Nifecaine is also used to associated treatment for these conditions: Achalasia, Anal Fissures, Chronic Stable Angina Pectoris, High Blood Pressure (Hypertension), Hypertensive Emergency, Premature Labour, Proctalgia, Pulmonary Edemas, Pulmonary Hypertension (PH), Raynaud's Phenomenon, Ureteral Calculus, Vasospastic Angina

How Nifecaine works

Nifedipine blocks voltage gated L-type calcium channels in vascular smooth muscle and myocardial cells. This blockage prevents the entry of calcium ions into cells during depolarization, reducing peripheral arterial vascular resistance and dilating coronary arteries. These actions reduce blood pressure and increase the supply of oxygen to the heart, alleviating angina.

Dosage

Nifecaine dosage

Nifedipine 10 mg:

• Angina: Initially 10 mg 3 times daily with food increased to 20 mg 3 times daily if necessary, in elderly patients, initially 5 mg 3 times daily.
• Raynaud's Phenomenon: 10 mg 3 times daily; maximum 60 mg daily. In urgent cases, the tablet should be dissolved under the tongue like a sublingual tablet. The effect occurs within some minutes.

Nifedipine 20 mg:

The starting dose for patients, not previously prescribed Nifedipine products is one tablet once daily. The recommended dose in hypertension and angina prophylaxis is 20 mg twice daily during or after food. Dosage may be adjusted within the range 10 mg twice daily to 40 mg twice daily.

Patients with liver dysfunction should commence therapy with 10 mg twice daily with careful monitoring.

Patients with renal impairment do not require adjustment of dosage.

Side Effects

Headache, flushing, lethargy, gravitational oedema rash, nausea, increased frequency of micturation, eye pain, gum hyperplasia, depression, tremor, photosensitivity and few cases of jaundice have been reported. These reactions may regress on discontinuation of therapy. Its introduction may induce attacks of ischaemic pain in some patients with angina pectoris.

Toxicity

The oral LD₅₀ in rats is 1022mg/kg and in mice is 202mg/kg.

Patients experiencing an overdose may present with hypotension, sinus node dysfunction, atrioventricular node dysfunction, and reflex tachycardia. Overdose may be managed by monitoring cardiovascular and respiratory function; elevating extremities; and administering vasopressors, fluids, and calcium infusions.

Precaution

Tablets should be swallowed whole and should not be bitten, chewed or broken up. It should be used with caution in patient whose cardiac reserve is poor. Should be withdrawn if ischaemic pain occurs or existing pain worsens shortly after initiating treatment. Use in diabetic patients requires adjustment of their control. Since the absorption of the drug could be modified by renal disease, caution should be exercised in treating such patients.

Interaction

• ACE inhibitors: Enhanced hypotensive effect.
• Anti-arrythmics: Plasma concentration of quinidine is reduced.
• Anti-bacterials: Rifampicin possibly increases metabolism of Nifedipine.
• Anti-epileptics: Plasma concentration of phenytoin increases.
• Antipsychotics: Enhanced hypotensive effect.
• β-blockers: Occasionally severe hypotension and heart failure may occur.
• Cyclosporin: Plasma concentration of Nifedipine possibly increases.
• Muscle relaxants: Effect of muscle relaxants e.g. tubocurarine increases.
• Ulcer healing drugs: Metabolism of Nifedipine increases.

Volume of Distribution

The steady state volume of distribution of nifedipine is 0.62-0.77L/kg and the volume of distribution of the central compartment is 0.25-0.29L/kg.

Elimination Route

Sublingual dosing leads to a C_max of 10ng/mL, with a T_max of 50min, and an AUC of 25ng*h/mL. Oral dosing leads to a C_max of 82ng/mL, with a T_max of 28min, and an AUC of 152ng*h/mL.

Nifedipine is a Biopharmaceutics Classification System Class II drug, meaning it has low solubility and high intestinal permeability. It is almost completely absorbed in the gastrointestinal tract but has a bioavilability of 45-68%, partly due to first pass metabolism.

Half Life

The terminal elimination half life of nifedipine is approximately 2 hours.

Clearance

The total body clearance of nifedipine is 450-700mL/min.

Elimination Route

Nifedipine is 60-80% recovered in the urine as inactive water soluble metabolites, and the rest is eliminated in the feces as metabolites.

Pregnancy & Breastfeeding use

There are no adequate and well controlled studies in pregnant women. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Contraindication

Cardiogenic shock, advanced aortic stenosis, nursing mothers, GI obstruction, inflammatory bowel disease, hypotension.

Storage Condition

Protect from strong light, store in a cool place in the original pack

Innovators Monograph

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