Herb-Drug Interactions: Policosanol

Types, sources and related compounds

Octacosanol.

Constituents

Policosanol consists of a mixture of alcohols with octacosanol being the major component. Triacontanol and hexacosanol are also present but in lesser amounts.

Use and indications

Policosanol is isolated from sugar cane wax and, because of its lipid-lowering and antiplatelet properties, is mainly used for cardiovascular disorders. It is also being investigated for possible use in the treatment of Parkinson’s disease, and for enhancing athletic performance.

Pharmacokinetics

Policosanol did not alter the metabolism of phenazone (antipyrine) in dogs. Phenazone is used as a probe drug to assess the effects of other drugs on hepatic enzyme induction and inhibition. This finding therefore suggests that policosanol is unlikely to induce or inhibit the metabolism of other drugs that are substrates of hepatic enzymes.

Interactions overview

Policosanol has antiplatelet effects, which may be additive with other antiplatelet drugs, and could theoretically increase the risk of bleeding in patients taking anticoagulants. Policosanol may also enhance the blood pressure-lowering effects of some antihypertensives.

Policosanol + Anticoagulants

The interaction between policosanol and anticoagulants is based on a prediction only.

Clinical evidence

No interactions found.

Experimental evidence

Policosanol 200mg/kg did not prolong the bleeding time warfarin 200 micrograms/kg given for 3 days in rats.

Mechanism, importance and management

Although policosanol did not enhance the prolongation of the bleeding time induced by warfarin in rats, policosanol has antiplatelet properties and increased bleeding has been reported when it was given with aspirin, see below, so bear this in mind if excessive bleeding is seen.

Policosanol + Antiplatelet drugs

Policosanol has antiplatelet effects, which may be additive with those of other antiplatelet drugs.

Clinical evidence

In a randomised study, four groups, each containing 10 or 11 subjects, were given placebo, policosanol 20 mg daily, aspirin 100 mg daily or both drugs together, for 7 days. Adrenaline-induced platelet aggregation was reduced in the group given aspirin and policosanol by about 35% more than in the group given aspirin alone: the effects of aspirin and policosanol were approximately additive. Furthermore, collagen-induced platelet aggregation was reduced in the group given aspirin and policosanol by about 10% more than in the group given aspirin alone. One patient taking both drugs suffered from bleeding gums. There was no significant effect on coagulation time. A 3-year study, primarily designed to assess the safety and efficacy of policosanol in patients taking beta blockers, included 32 patients taking antiplatelet drugs (mainly aspirin). No adverse effects related to bleeding were reported.

Experimental evidence

No relevant data found.

Mechanism

Additive antiplatelet effects.

Importance and management

The concurrent use of two conventional antiplatelet drugs is not uncommon, and so concurrent use of policosanol and aspirin need not be avoided. However, because platelet aggregation was reduced significantly, and a bleeding event was experienced, caution is perhaps warranted when taking policosanol supplements with aspirin or any other antiplatelet drug.

Policosanol + Beta blockers

Policosanol appears to increase the blood pressure-lowering effects of beta blockers.

Clinical evidence

In a randomised study in patients (aged 60 to 80 years) taking beta blockers, the addition of policosanol 5 mg tablets daily (titrated to a dose of 2 to 4 tablets) found that the average blood pressure was reduced from about 141/83mmHg to 131/81 mmHg after oneyear, and 126/79 mmHg after 3 years. The efficacy of policosanol was not reduced and adverse effects were actually slightly lower in the policosanol group.

Experimental evidence

In a study in hypertensive rats, a single 200-mg/kg oral dose of policosanol enhanced the blood pressure-lowering effects of intravenous and oral propranolol without increasing the reduction in heart rate induced by propranolol.

Mechanism

Policosanol is thought to reduce vascular resistance.

Importance and management

Policosanol increased the blood pressure-lowering effects of beta blockers and the clinical study suggests that the effect is gradual and beneficial. Furthermore, adverse effects related to hypotension were not reported. It therefore appears that, as with other conventional antihypertensives, policosanol may increase the effects of the beta blockers and so some caution is warranted, but no adverse effects such as first-dose hypotension would be expected.

Policosanol + Food

No interactions found.

Policosanol + Herbal medicines

No interactions found.

Policosanol + Nifedipine

Policosanol does not appear to affect the blood pressure-lowering effects of nifedipine.

Clinical evidence

A 3-year study, primarily designed to assess the safety and efficacy of policosanol in patients taking beta blockers, included 28 patients taking calcium-channel blockers (unnamed). No adverse effects related to hypotension were reported.

Experimental evidence

In a study in hypertensive rats, a single 200-mg/kg oral dose of policosanol did not affect the blood pressure-lowering effects of intravenous nifedipine 300 micrograms/kg given 2 hours later.

Mechanism

Policosanol is thought to reduce vascular resistance.

Importance and management

There appears to be no reason to avoid taking policosanol supplements with nifedipine. However, additive blood pressure-lowering effects seem possible, see beta blockers.

Policosanol + Phenazone (Antipyrine)

The information regarding the use of policosanol with phenazone (antipyrine) is based on experimental evidence only.

Clinical evidence

No interactions found.

Experimental evidence

A study in dogs found that the pharmacokinetics of an intravenous dose of phenazone 10 mg/kg were not affected by oral treatment with policosanol, 25mg/kg daily for 21 days.

Mechanism

No mechanism expected.

Importance and management

On the basis of the results from this animal study, there appears to be no reason to avoid taking policosanol supplements with phenazone.

Policosanol + Sodium nitroprusside

The interaction between policosanol and sodium nitroprusside is based on experimental evidence only.

Clinical evidence

No interactions found.

Experimental evidence

A study found that the antiplatelet and hypotensive effect of sodium nitroprusside was greater in rats that had been pre-treated with a single 200-mg/kg oral dose of policosanol, than in animals that had not received policosanol.

Mechanism

Both policosanol and sodium nitroprusside have antiplatelet effects. These appear to be additive. Policosanol reduces vascular resistance and has been shown to enhance the blood pressure-lowering effects of other antihypertensives.

Importance and management

The clinical significance of this finding is unclear, but bear it in mind in case of an unexpected response to treatment.