Isradipine

Registered South African indications:

• Hypertension

Contraindications

• Hypersensitivity to the active ingredient or any of its excipients
• Breastfeeding

Cautions

• Pregnancy
• Moderate to severe renal impairment
• Severe hepatic impairment
• Elderly
• Obstructive coronary disease
• Severe aortic stenosis
• Heart failure
• Hypertrophic cardiomyopathy
• Sick sinus syndrome
• Recent myocardial infarction
• Conduction defects
• Ischaemic heart disease
• Low systolic blood pressure
• May impair ability to drive and operate machinery

Forms avail. in SA and covered in this monograph: tab, cap

Hypertension - mild to moderate

• Oral (tab): 2.5mg, 12hrly; Max: 5mg/24hrs 
• Oral (cap): 5mg, 24hrly; Max: 5mg/24hrs 

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Isradipine tablet: If blood pressure is not adequately controlled after 4 weeks of treatment, patients may require a dosage of 5mg 12hrly, or if more appropriate, the addition of a low dose of another antihypertensive agent

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Isradipine capsule: If one 5mg capsule once daily is not sufficiently effective after 4 weeks of treatment, the addition of another antihypertensive is recommended

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Isradipine capsules must be swallowed whole

Not established for use in children below 18 years

Pregnancy

• Caution; not recommended
• Limited human data with animal data suggest a low risk for teratogenicity
• The drug is not teratogenic in rats or rabbits at doses 150 and 25 times the maximum recommended human dose, respectively. Embryotoxicity was not observed in either species at doses that were not maternally toxic
• Several studies have described the use of isradipine in pregnant women. No adverse foetal effects attributable to the drug were observed
• lsradipine crosses the placenta to the fetus at term
• An open-label study comparing the antihypertensive effect of isradipine with hydralazine and methyldopa in women with severe preeclampsia have shown no differences in the outcomes in terms of gestational age at birth, Apgar scores, and birth weight

Breastfeeding

• Contraindicated
• It is not known if isradipine is present in breast milk
• Due to potential adverse reactions in the breastfeeding infant, a decision should be made whether to discontinue breastfeeding or to discontinue the drug, considering the importance of treatment to the mother

Renal impairment

• eGFR ≥80-90 ml/min/1.73 m²: No dose adjustment recommended
• eGFR ≤79 ml/min/1.73 m²: Caution; dose adjustment recommended
  Initiate treatment with 1.25mg twice a day
  Monitor renal function and discontinue agent if eGFR declines below 30 mL/min/1.73 m²

Hepatic impairment

• Mild to moderate (Child-Pugh Classes A & B): No dose adjustment recommended
• Severe (Child-Pugh Class C): Caution; dose adjustment recommended
  Reduce the daily dose to 1.25mg, twice daily
  Monitor liver function test

Elderly

• Caution; no dose adjustment recommended
  Start with a low dose of 1,25 mg (half a tablet) twice a day, and slowly up-titrate to adult dosages

Porphyria Information

• Probably not porphyrinogenic (PNP)

Drugs in Sport

• Permitted - No warnings

Central Nervous System Disorders

• Headache 
• Fatigue
• Dizziness
• Depression
• Drowsiness
• Insomnia
• Lethargy
• Nervousness
• Syncope
• Cerebral ischaemia

Cardiovascular Disorders

• Oedema
• Palpitation
• Tachycardia
• Cardiac ischaemia
• Ischaemic chest pain
• Atrial fibrillation
• Ventricular fibrillation
• Cardiac failure
• Cerebrovascular accident
• Hypotension
• Myocardial infarction
• Transient ischaemic attacks

Respiratory Disorders

• Dyspnea
• Cough

Gastrointestinal Disorders

• Nausea and vomiting
• Abdominal discomfort
• Diarrhoea
• Constipation
• Sore throat
• Gastrointestinal disturbances
• Gingival hyperplasia
• Xerostomia

Hepatobiliary Disorders

• Liver function abnormalities
• Increased serum transaminases

Genitourinary Disorders

• Urinary frequency
• Decreased libido
• Impotence
• Nocturia

Musculoskeletal Disorders

• Weakness
• Foot cramps
• Leg cramps

Skin and Subcutaneous Tissue Disorders

• Skin rash
• Erythema multiforme
• Flushing
• Hyperhidrosis
• Paresthesia
• Pruritus
• Urticaria

Immune, Blood and Lymphatic System Disorders

• Leukopenia
• Hypersensitivity reactions
• Fever
• Increased serum transaminases

Sensory Disorders

• Visual disturbance
• Eye pain
• Transient blindness
• Numbness

Other

• Localized peripheral oedema

• CYP3A4 inhibitors
• Cimetidine
• Azole antifungals
• CYP3A4 inducers
• Rifampicin
• Phenobarbital
• Anticonvulsant agents
• Propranolol

• Blood pressure
• Heart rate

Specific cases may require 

• Blood glucose

Isradipine is a dihydropyridine calcium antagonist with a high affinity for calcium channels in arterial smooth muscle versus those in the myocardium, thus it dilates arterial vascular beds, in particular those of the heart, brain and skeletal muscle without depressing cardiac function. As a consequence of peripheral vasodilation, total peripheral resistance is reduced and arterial blood pressure is lowered.

Tablet 2.5mg

• Dynacirc (Norvatis) originator

Capsule 5mg

• Dynacirc SRO (Norvatis) originator