Omacor

Omacor contains highly purified omega-3 polyunsaturated fatty acid ethyl esters, principally eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

It is the only prescription omega-3 preparation licensed in the UK and is indicated for two distinct conditions: hypertriglyceridaemia (type IIb/III or IV) as an adjunct to diet when dietary measures alone are insufficient, and as secondary prevention following myocardial infarction, in combination with standard post-MI pharmacotherapy.

The lipid-lowering mechanism involves reduced hepatic VLDL synthesis and enhanced triglyceride clearance.

In the GISSI-Prevenzione trial, omega-3-acid ethyl esters reduced all-cause mortality by 20% and sudden cardiac death by 45% when started within 3 months of MI.

However, subsequent trials (ASCEND, VITAL, STRENGTH) in broader cardiovascular populations have shown more modest or inconsistent benefits, leading to updated NICE guidance that no longer recommends routine omega-3 supplementation for cardiovascular prevention in all patients.

Omacor remains licensed for its specific indications and may be prescribed where individual clinical judgement supports its use.

Swallow capsules whole with water during or after meals. Do not puncture or chew the capsules.

For hypertriglyceridaemia, the usual dose is 2 capsules twice daily with food; this can be increased to 4 capsules twice daily under specialist supervision if response is inadequate after 2 months.

For post-MI secondary prevention, the dose is 1 capsule once daily. Response should be assessed after 2 months by checking fasting triglyceride levels.

If used for hypertriglyceridaemia, dietary measures (reduced alcohol, sugar, and saturated fat intake) must be continued alongside treatment.

Regular monitoring of liver function and LDL cholesterol is advisable, as omega-3 acids can increase LDL levels while lowering triglycerides.

Hypertriglyceridaemia: Initially 2 capsules (2 g) daily, increasing to 4 capsules (4 g) daily if triglyceride reduction is insufficient after 2 months. Take in divided doses with food.

Post-myocardial infarction: 1 capsule (1 g) once daily, taken with food.

No dose adjustment for renal impairment. In hepatic impairment, use with caution due to potential effects on hepatic lipid metabolism; monitor liver function.

No specific dose adjustment for elderly patients. Treatment efficacy should be reassessed regularly.

Side effects per SmPC frequency categories.

Common (≥1/100 to <1/10): Dyspepsia, nausea, abdominal pain, eructation (fishy), diarrhoea, abdominal distension.

Uncommon (≥1/1,000 to <1/100): Hyperglycaemia, dizziness, taste disturbance, headache, vomiting, gastroenteritis, rash, acne, elevated liver transaminases, elevated LDL cholesterol.

Rare (≥1/10,000 to <1/1,000): Hypotension, epistaxis, gastrointestinal haemorrhage, hepatic disorder, urticaria.

Very rare (<1/10,000): Haematuria.

The most commonly troublesome side effect is fishy eructation, which can be minimised by taking capsules with food or freezing them before ingestion.

LDL cholesterol may rise during treatment for hypertriglyceridaemia, requiring concurrent statin therapy in some patients.

Monitor LDL cholesterol during treatment for hypertriglyceridaemia, as a paradoxical rise may occur, potentially necessitating additional statin therapy.

Monitor liver function, particularly at the higher doses used for hypertriglyceridaemia.

Omega-3 acids have a mild antiplatelet effect; exercise caution in patients on anticoagulants (warfarin, DOACs) or antiplatelet agents (aspirin, clopidogrel), as the bleeding time may be prolonged.

The clinical significance of this interaction at standard doses is generally modest, but monitor for signs of bleeding.

Patients with known allergy to fish should not take Omacor, as the active ingredients are derived from fish oil.

The GISSI-Prevenzione trial results may not be fully generalisable to contemporary practice where background statin and RAAS inhibitor use is near universal.

Omacor is contraindicated in patients with hypersensitivity to omega-3-acid ethyl esters, soya, peanut, or any excipient (the capsules contain soya lecithin).

It should not be used in exogenous hypertriglyceridaemia (type I hyperlipoproteinaemia). Caution in severe hepatic impairment due to insufficient safety data.