Chapter 21 – Herbal Medications

Chapter 21 Herbal Medications

A. Agatha Crerar-Gilbert

Key Points

1. Although seen as beneficial and safe, herbal medications and supplements are not completely risk free.
2. Use of herbal medications is largely unregulated and herbal medicines may vary in composition and amount of herbs in their mixtures and may be contaminated with other herbs and non-herbal medicines.
3. Herbal medications have a number of interactions and side effects which are relevant to surgery and anaesthesia.
4. Knowledge and documentation of the use of herbal medicines is important to anticipate, prevent and manage problems that may arise from herbal medications taken during the perioperative period.
5. While recommendations for discontinuation of individual herbal medications vary from 36 hours to 9 days, a more general approach is that in elective surgery, herbal medications should be discontinued 2 weeks prior to surgery.

Perioperative management of cardiovascular, anticoagulation (including bridging therapy), diabetes, steroids and psychotropic medication is detailed elsewhere in the related chapters. In this chapter we will consider herbal medications with relevance to the forthcoming surgery and anaesthesia.

Herbal medicines are used frequently in the United Kingdom and are perceived to have a good safety profile (Skinner & Rangasami, 2002). Survey of patients undergoing elective surgery found use of herbal medicines in 57 per cent of patients. The most common were echinacea (48 per cent), aloe vera (30 per cent), ginseng (28 per cent), garlic (27 per cent) and ginkgo biloba (22 per cent) (Adusumilli et al., 2004). For a variety of reasons, patients do not volunteer information about intake of herbs and a large number of anaesthetic departments have no appropriate practices in place to acquire and record history on use of herbal medicines (Hogg & Foo, 2010).

Although seen as beneficial and safe, herbal medicines are not completely risk free. Examples of related complications include myocardial infarction from food supplements containing ephedra alkaloids, bilateral subdural haematomas associated with ginkgo, epidural haematoma due to excessive garlic ingestion and acute renal failure in patients who had been taking Chinese herbal slimming pills. There is also evidence of organ rejection secondary to reduced bioavailability of immunosuppressants with concomitant St John’s wort administration and immunosuppression and post-operative infections with long-term echinacea use (Hogg & Foo, 2010).

Use of herbal medicines is largely unregulated as they are marketed as food supplements or cosmetics and exempted from the product licensing under the Medicines Act 1968. Herbal medicines may vary in composition and amount of herbs in their mixtures and may be contaminated with other herbs and non-herbal medicines. This variation limits reliability of research on action and side effects of herbal medicines.

Herbal medicines may affect perioperative patients by their effects on patients’ physiology, side effects and interaction with other drugs given perioperatively. Table 21.1 gives an account of commonly used herbal medicines, and summarises their significance with regards to surgery and perioperative recommendations.

Table 21.1 Summary of commonly used herbal medicines, known effects, interactions, complications and perioperative recommendations.

Herb	Pharmacological effect	Interactions	Potential Complications	Recommended stopping time prior to surgery
Ginseng	central stimulant, hypertension, hypoglycaemia, inhibits platelet aggregation, diminishes effect of vitamin K antagonists	Warfarin	Reduces the efficacy of anticoagulants, potentiates hypoglycaemia in type II diabetes mellitus, hypertension	7 days, ideally 2 weeks
Panax quinquefolius
Panax ginseng
Garlic	inhibits platelet aggregation, antihypertensive, hypoglycaemic	antidiabetic drugs	perioperative bleeding, neuroaxial blockade, bleeding tendency with NSAID / Warfarin	7 days, ideally 2 weeks
Allium sativum		antidiabetic drugs		7 days, ideally 2 weeks
Gingko	inhibits platelet-activating factor, antioxidant, modulates neurotransmitter activity	Warfarin, NSAID	may potentiate action of other platelet inhibitors, risk of bleeding especially with Warfarin and NSAIDs or neuroaxial block	at least 36 hours, ideally 2 weeks
Ginkgo biloba		Warfarin, NSAID		at least 36 hours, ideally 2 weeks
St. John’s wort	Central inhibition of reuptake of serotonin, noradrenaline and dopamine, induction of cytochromes (CYP) P4503A4 and CYP 2C9	immunosuppressants, anticoagulants, anticonvulsants, Digoxin	decreased effectiveness of alfentanil, midazolam, lignocaine, calcium channel blockers and digoxin, may interact with sympathomimetics, inducing hypertension and arrhythmias	at least 5 days but preferably 9 days,
Hypericum perforatum				ideally 2 weeks
Echinacea	Stimulation of the immune system, with long term may be immunosuppressive	corticosteroids	reduced effectiveness of immunosuppressants, potential for wound infection with long-term use, hepatotoxicity especially when used with other hepatotoxic drugs	continue in most cases, stop if immunosuppression required
Echinacea purpurea		corticosteroids		continue in most cases, stop if immunosuppression required
Valerian	Acts through modulation of γ- aminobutyric acid neurotransmission and receptor function		Potentiates sedative effects of anaesthetic agents. Acute withdrawal reaction with sudden withdrawal requiring treatment with benzodiazepines	dose needs to be tapered in several weeks preceding surgery.
Valeriana officinalis
Chinese herbal medicines	Largely unknown	Largely unknown	risk of hypotension or hypertension, delayed awakening and decreased renal blood flow	No reliable data, ? 2 weeks