Nifedipine

Indications

Nifedipine is used for: Hypertension, Angina pectoris, Raynaud's syndrome, Stroke prevention

Adult Dose

Oral Hypertension Adult: Immediate-release: Initially, 5 mg tid. Maintenance: 10-20 mg tid. Extended-release: Initially, 10-40 mg bid, or 20-90 mg once daily. Angina pectoris Adult: Immediate-release: Initially, 10 mg tid. Maintenance: 10-20 mg tid. Extended-release: 10-40 mg bid or 30-60 mg once daily. Raynaud's syndrome Adult: Immediate-release: 5-20 mg tid. Elderly: Dose reduction may be necessary. Hepatic impairment: Dose reduction may be necessary.

Child Dose

Renal Dose

Administration

Immediate-release: May be taken with or without food. Avoid grapefruit juice. Retard, GITS & OROS: May be taken with or without food. Avoid grapefruit juice. Swallow whole, do not chew/crush.

Contra Indications

Acute MI, cardiogenic shock, acute unstable angina, treatment of anginal attack in chronic stable angina.

Precautions

Patients w/ hypotension, poor cardiac reserve, heart failure, severe aortic stenosis, DM, underlying severe GI narrowing (extended-release tab). Avoid abrupt withdrawal as it may casue rebound angina. Hepatic impairment. Elderly. Pregnancy and lactation. Patient Counselling Discontinue if ischaemic pain follows after admin. Monitoring Parameters Monitor BP, heart rate. Lactation: Drug is distributed into breast milk; manufacturer suggests discontinuing drug or refraining from nursing (however, American Academy of Pediatrics states that drug is safe for nursing)

Pregnancy-Lactation

Interactions

Enhanced antihypertensive effects w/ other antihypertensives, aldesleukin, and antipsychotics. Concomitant use w/ fentanyl during surgery caused severe hypotension. May modify insulin and glucose responses. Attenuation of tachycardic effect when used w/ benazerpril. Prothrombin time may be increased w/ coumarin anticoagulants. Increased serum levels w/ CYP3A4 inhibitors (e.g. azole antifungals, cimetidine, erythromycin, HIV-protease inhibitors, nefazodone, fluoxetine, quinupristin/dalfopristin). Potentially Fatal: Decreased bioavailability and efficacy w/ strong CYP3A4 inducers (e.g. rifampicin, phenytoin, carbamazepine).

Side Effects

Side effects of Nifedipine : >10% Peripheral edema (10-30%), Dizziness (23-27%), Flushing (23-27%), Headache (10-23%), Heartburn (11%), Nausea (11%) 1-10% Muscle cramps (8%), Mood change (7%), Nervousness (7%), Cough (6%), Dyspnea (6%), Palpitations (6%), Wheezing (6%), Hypotension, transient (5%), Urticaria (2%), Pruritus (2%), Constipation (<2%), Chest pain (<2%) Frequency Not Defined Gingival hyperplasia, Agranulocytosis, Erectile dysfunction

Mode of Action

Nifedipine prevents Ca ion from entering the slow channels of cardiac and smooth muscles during depolarisation, producing peripheral and coronary vasodilatation. It reduces afterload, peripheral resistance and BP; increases coronary blood flow and causes reflex tachycardia. It has little or no effect on cardiac conduction and rarely has negative inotropic activity.