Hawthorn- Medicinal Uses, Interactions, Side Effects, Dosage

Hawthorn- Uses and Benefits, Preparations and Dosage

<p><strong>Hawthorn </strong></p> <p>Hawthorn is a member of the rose family and the genus Crataegus. The most commonly employed species of hawthorn are C. <em>laevigata </em>(also known as C. <em>oxyacantha) </em>and C. <em>monogyna. </em>Herbal formulations may contain a mixture of these species. </p> <p><strong>Uses and Benefits:</strong></p> <p>In modern herbal medicine, hawthorn is primarily used to treat congestive heart failure (CHF). Other clinical applications have included therapy for angina and coronary artery disease, hypertension, and cardiac arrhythmias. Traditionally, hawthorn has been considered a "cardiotonic" herb. </p> <p><strong>Pharmacology: </strong></p> <p>Hawthorn differs from foxglove in that it does not produce cardioactive glycosides. Some of the chemical con­stituents in hawthorn include oligomeric and polymeric procyanidins, flavonoids (e.g., hyperoside, vitexin- and acetyl-vitexin­2"-O-rhamnoside), catechins, triterpene saponins, and amines. Of these, the oligomeric procyanidins (OPCs) and flavonoids are most likely to contribute pharmacologic activity . In animal and <em>in vitro </em>studies, flavonoids inhibit phosphodiesterase (PDE) activ­ity. As a result, they may promote vasodilation and coronary blood flow, decrease vascular resistance, and increase heart rate and contractility. The vasodilation may be due to PDE inhibition or the release of endothelium-derived vasoactive factors, such as nitric oxide. The inotropic effects, however, appear to be unre­lated to PDE or beta-sympathomimetic effects. <em>In vitro, </em>Crataegus inhibits the Na+/K+ ATPase in human myocardial cells, similar to the digitalis glycosides, leading to a rise in intracellular calcium and enhanced force of contraction. </p> <p>In contrast to other inotropic drugs (e.g., digoxin, amrinone, milrinone, epinephrine), hawthorn increases cardiac refractori­ness by prolonging the action potential duration (similar to a Class antiarrhythmic) and delaying sodium channel recovery (similar to a Class antiarrhythmic). Other inotropes shorten the refractory period, and thus can induce arrhythmias. Standardized hawthorn extracts reduce ischemia-induced ar­rhythmias and markers of ischemic injury in most animal models. One recent study, however, demonstrated a proarrhythmic effect of hawthorn.</p> <p>Although unlikely to be related to its inotropic activity, flavonoid­rich preparations exhibit antioxidant properties and reduce para­meters of lipid peroxidation in animal models of atherosclerosis. The OPC fraction also has antioxidant effects. . <em>In vitro, </em>various constituents in hawthorn have been shown to inhibit platelet ag­gregation by blocking thromboxane A2 synthesis, and to stimulate platelet aggregation by enhancing prostacyclin synthesis. </p> <p><strong>Clinical Trials:</strong></p> <p>Hawthorn has been primarily studied in pa­tients with mild CHF (mostly New York Heart Association Class II) in at least clinical trials from European countries. Only one study was published in the English language, but all the studies have been reviewed and summarized. Seven of these clinical trials were controlled and had similar outcome measurements; five were randomized and all were double-blinded. Six of the seven were placebo-controlled, and one compared hawthorn ex­tract to captopril, an angiotensin-converting enzyme inhibitor. These controlled trials contained 30-136 patients each, lasted 4-8 weeks, and used doses of standardized hawthorn extract products ranging from 160 to 900 mg/day. Primary study out­comes were the pressure rate product (PRP)-the product of heart rate multiplied by systolic blood pressure divided by 100; exercise tolerance as measured by a bicycle ergometer; and subjective symptoms (e.g., shortness of breath, fatigability). </p> <p>Of the six placebo-controlled trials, four of five noted statisti­cally significant improvements in the PRP, three of four in exercise tolerance, and five of six in subjective symptoms. One placebo­controlled trial that did not observe any benefit in PRP, work toler­ance, or symptoms had a study duration of 4 weeks, compared to 8 weeks for most of the others. This study, however, did note a significant improvement in ejection fraction in the hawthorn group. The trial that compared hawthorn extract (900 mg/day) to low doses of captopril (37.5 mg/day) for 8 weeks noted significant . equivalent improvements in work tolerance and severity of symptoms. </p> <p><strong>Adverse Effects:</strong></p> <p>Hawthorn is very well tolerated. Mild gastrointestinal effects and headaches were reported in < 2% of patients in the controlled clinical trials. A surveillance study observed 72 side effects in 1.3% of 3664 patients with mild CHF; 26 of these appeared to be related to the use of the extract. The most common side effects were stomach upset, palpitations, headache, and dizziness. A mild but significant lowering of blood pressure and heart rate also has been observed in some trials; this may have been an appropriate response to therapy in heart failure patients with initial hypertension and tachycardia. </p> <p><strong>Side Effects and Interactions:</strong></p> <p>Hawthorn extract may potentiate the action of digoxin, but the effect has not been well characterized. This combination was employed to decrease a dosage of cardiac glycosides. Close monitoring is warranted if used concurrently with digoxin, other inotropes, and antiarrhythmic drugs. </p> <p><strong>Cautions: </strong>Hawthorn has mixed effects on platelet aggregation <em>in vitro ; </em>however, there are no reports of clinical hematologic effects, and none are expected <em>in vivo. </em>There are no data on safety during pregnancy or lactation. </p> <p><strong>Preparations </strong><strong>& </strong><strong>Doses:</strong></p> <p>The two extracts most often employed in the European controlled clinical trials were WS 1442 (Crataequtt) and LI 132 (Faros). Crataegutt is a leaf and flower extract ;tandardized to 18.75% OPCs. Faros is prepared from the leaves, flowers, and berry and is standardized to 2.2% f1avonoids. Only Crataegutt is marketed in the U.S., as HeartCare (Nature's Way). Doses in the clinical trials ranged widely from 160 to 900 mg/day, usually in 2-3 divided doses. These daily doses represent about 4-30 mg of flavonoids and 30-160 mg of OPCs, respectively.</p> <p><strong>Summary Evaluation </strong></p> <p>Objective improvements for patients with mild CHF have been consistently reported in many short-term controlled trials, imply­ing promising effects for this herb. However, methodologic quality cannot be assured because the majority of clinical trials are not available in English. Moreover, unlike standard pharmaceutical treatments for CHF that have been well documented to reduce morbidity and mortality when used chronically, hawthorn has not been studied beyond 2 months of use, and results of one study demonstrated hawthorn to be equivalent to a very low dose of an ACE inhibitor. Thus, patients should be discouraged from using hawthorn alone, even for the treatment of mild CHF. In addition, heart failure should be managed by experienced clinicians, and poorly supervised use of hawthorn may expose the patient to un­needed risks. </p>

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