Calcium channel blockers blunt postural cutaneous vasoconstriction in hypertensive patients

Etiology of Drug-Induced Edema: A Review of Dihydropyridine, Thiazolidinedione, and Other Medications Causing Edema

Edema is an accumulation of fluid in the body's tissues that affects millions of Americans yearly. It can affect multiple body parts, for example, the brain or eyes, but often occurs in the periphery, including the feet and legs. Medications, such as dihydropyridine and thiazolidinediones (TZDs), can be the etiology of edema. Edema can develop in association with problems in the vasculature or lymphatic flow. In recent years, a better understanding of these drug-induced mechanisms has been appreciated. Specifically, dihydropyridines can increase hydrostatic pressure and cause selective pre-capillary vessel vasodilation. TZDs can cause edema through increased vascular permeability and increased hydrostatic pressure. Specifically, peroxisome proliferator-activated receptor gamma (PPARγ) stimulation increases vascular endothelial permeability, vascular endothelial growth factor (VEGF) secretion, renal sodium, and fluid retention. Other drugs that can cause edema include neuropathic pain agents, dopamine agonists, antipsychotics, nitrates, nonsteroidal anti-inflammatory (NSAIDS), steroids, angiotensin-converting enzyme (ACE) inhibitors, and insulin. There are various clinical presentations of edema. Since multiple mechanisms can induce edema, it is important to understand the basic mechanisms and pathophysiology of drug-induced edema. Edema can even become fatal. For example, angioedema can occur from ACE inhibitor therapy. In this regard, it is considered a medical emergency when there is laryngeal involvement. This review aims to thoroughly appreciate the multiple causes of drug-induced edema and the ways it can be treated or prevented.

Drug-induced peripheral oedema: An aetiology-based review

Many drugs are responsible, through different mechanisms, for peripheral oedema. Severity is highly variable, ranging from slight oedema of the lower limbs to anasarca pictures as in the capillary leak syndrome. Although most often noninflammatory and bilateral, some drugs are associated with peripheral oedema that is readily erythematous (eg, pemetrexed) or unilateral (eg, sirolimus). Thus, drug-induced peripheral oedema is underrecognized and misdiagnosed, frequently leading to a prescribing cascade. Four main mechanisms are involved, namely precapillary arteriolar vasodilation (vasodilatory oedema), sodium/water retention (renal oedema), lymphatic insufficiency (lymphedema) and increased capillary permeability (permeability oedema). The underlying mechanism has significant impact on treatment efficacy. The purpose of this review is to provide a comprehensive analysis of the main causative drugs by illustrating each pathophysiological mechanism and their management through an example of a drug.

A Review of Microvascular Measurements in Wound Healing

The microcirculatory evaluation in patients affected by arteriopathic or venous ulcers is usually carried out using laser Doppler flowmetry, transcutaneous oxygen (transcutaneous pressure of oxygen, TcPO2), and carbon dioxide (transcutaneous pressure of carbon dioxide, TcPCO2) measurements and capillaroscopy. These techniques provide significant pathophysiologic and prognostic information. TcPO2 and TcPCO2 diagnose and classify the extent of arterial disease in the leg ulcers caused by arterial disease; the prognostic value is recognized, though doubts about its prognostic potential exist in the case of leg ulcer. Laser Doppler flowmetry is able to identify the first functional impairment in the early stages of the arterial disease and in the complicated venous insufficiency. Capillaroscopy gives us morphological and quantitative parameters of the capillary bed that is damaged in arteriopathic and venous ulcers; nevertheless, it does not provide us with definite prognostic indexes. Combining the 3 methods may contribute to yield objective measures in the clinical management of lower extremity ulcers.

The use of an extract of Hypericum perforatum and Azadirachta indica in a neuropathic patient with advanced diabetic foot

The successful use of an extract of Hypericum flowers (Hypericum perforatum) and nimh oil (Azadirachta indica; Hyperoil) in foot wounds with exposed bone in a patient with bilateral advanced diabetic ulcers, has been reported previously. It was hypothesised that this amelioration was linked with the improved glycaemic control and peripheral microvascular circulation. In this case report, the surprisingly successful outcome of another patient using Hyperoil for infection damaged diabetic foot, without prior use of surgical procedure, is described. The patient had no macrovascular pattern impairment. Diabetic foot healing paralleled with controlled local infection and enhanced glycaemic control. The outcome of this patient suggests that the effectiveness of this inexpensive therapy using Hyperoil for diabetic foot is not only linked with the presence of severe microvascular disorder, but also with the appropriate local treatment for ulcer being a must for its recovery.

Role of combination therapy in the treatment of hypertension: focus on valsartan plus amlodipine

Hypertension control is rare in clinical practice, particularly in high-risk patients. A large factor is therapeutic inertia deriving from poorly prescribed lifestyle changes, excess monotherapy use, and scarce on-treatment modifications. The use of drug combinations significantly improves blood pressure (BP) control; in particular, fixed combinations improve therapy without increasing daily pill intake, thereby favouring patient compliance and therapy continuation. The most widely used fixed combination is based on thiazide diuretics added to either angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs). Several large-scale clinical trials have been conducted showing that these combinations are effective in lowering BP. However, thiazide diuretics can reduce the metabolic benefits derived from renin-angiotensin-aldosterone system (RAAS) inhibitors in high metabolic risk patients. In contrast, ACE inhibitors or ARBs combined with dihydropyridine calcium channel antagonists (DHPCAs) exert a marked antihypertensive effect without decreasing metabolic protection by RAAS blockade. In the recent JIKEI heart study, approximately 60% of patients affected by hypertension, heart failure, coronary heart disease or their combination in the valsartan arm were simultaneously treated with DHPCAs. Of note, a 39% reduction in the primary endpoint of combined morbidity and mortality was reported in the valsartan compared with the non-valsartan arm. Furthermore, in a recent multinational study, 83% of 3161 hypertensive patients treated with valsartan and the DHCPA amlodipine reported a concontrolled BP after 8 weeks of treatment. As expected, amlodipine did not negatively influence the metabolic profile of patients, thereby supporting the role of ARB+DHPCA combinations as effective and promising tools in hypertension treatment. In summary, the combination of ARBs with DHPCAs is an effective strategy in hypertension treatment through synergy between their antihypertensive and vascular protective actions, persistent metabolic benefits deriving from RAAS inhibition, and reduced incidence of side effects.

Heterogeneous effect of calcium antagonists on leg oedema: a comparison of amlodipine versus lercanidipine in hypertensive patients

AIMS

To compare the effect of amlodipine, a prototype dihydropyridine calcium-channel blocker with lercanidipine, a newer dihydropyridine compound with lipophilic properties, on dependent oedema generation and interference with skin blood flow vasomotion in hypertensive patients.

DESIGN

Single-blind, sequence-randomized, cross-over comparison of amlodipine and lercanidipine. Drugs were given at equipotent doses (10 mg daily and 20 mg daily, respectively) in 22 never-treated mild-to-moderate hypertensive men (age: 48 +/- 5 years). Each treatment was administered for 2 weeks with a 2-week intervening period to restore baseline values.

MAIN OUTCOME MEASURES

Dependent oedema formation was quantified through leg weight changes (water displacement method). Blood pressure (the mean of at least 10 determinations) was recorded by an automated oscillometric device and skin blood flow (laser Doppler flowmetry) measured at the dorsum of the foot, both supine and with the limb passively placed 50 cm below the heart level, to evaluate the behaviour of cutaneous postural vasoconstriction, an autoregulatory mechanism that minimizes gravitational increases in capillary pressure and avoids fluid extravasation when standing.

RESULTS

Leg weight was increased by both drugs, but the increase was significantly greater during treatment with amlodipine than with lercanidipine. Blood pressure decreased to a similar extent and postural vasoconstriction was antagonized comparably during both treatments.

CONCLUSIONS

The oedema-forming potential of amlodipine is greater than that induced by lercanidipine, a difference which emerged in the presence of a comparable drop in blood pressure and could not be attributed to interference with postural vasoconstrictor mechanisms.

Foot volume increase on nifedipine is not prevented by pretreatment with diuretics

OBJECTIVE

Despite their natriuretic effects, dihydropyridine calcium-channel blockers (CCBs) often induce ankle oedema, probably due to vasodilation in the dependent legs. Since concomitant administration of frusemide does not prevent the acute increase in foot volume on nifedipine, we investigated whether diuretic pretreatment attenuates foot swelling on CCBs.

METHODS

In four separate experiments, 10 healthy volunteers received: (i) 20 mg of nifedipine without active pretreatment (pretreatment with placebo only); (ii) 20 mg of nifedipine after 5 days' treatment with amiloride 5 mg twice daily; (iii) 20 mg of nifedipine after 5 days' treatment with chlorthalidone 50 mg once daily; and (iv) no active drugs (pretreatment with placebo and placebo in place of nifedipine) as the control. Foot volumes were measured using an accurate water displacement technique (intra-individual coefficient of variance 0.27%).

RESULTS

Amiloride and chlorthalidone pretreatment induced marked volume depletion, with a 2-3% reduction in body weight, a 5-10% increase in haematocrit and a 14-23% increase in plasma colloid osmotic pressure. In addition, the mean +/- SEM foot volume after both chlorthalidone (1282 +/- 37 ml) and amiloride (1289 +/- 40 ml) was lower than without pretreatment (1315 +/- 38 ml) (P < 0.05). Neither amiloride nor chlorthalidone significantly influenced the acute increase in foot volume on nifedipine. However, due to pretreatment effects, the foot volume after nifedipine was higher (P < 0.05) without pretreatment (1356 +/- 36 ml) than after amiloride (1318 +/- 38 ml) or chlorthalidone (1319 +/- 37 ml). Amiloride significantly attenuated the natriuretic effect of nifedipine, whereas chlorthalidone prevented the nifedipine-induced rise in colloid osmotic pressure and haematocrit.

CONCLUSIONS

Diuretic pretreatment and the concomitant volume depletion did not prevent acute foot swelling on nifedipine, although the absolute foot volume remained lower after such pretreatment. Therefore diuretics mitigate the oedema of CCBs, but do not directly interfere with oedema formation.

Effect of beta-blockers on peripheral skin microcirculation in hypertension and peripheral vascular disease

OBJECTIVE

This study was undertaken to investigate the possible negative effect of beta-blockers on skin microcirculation in patients with intermittent claudication and hypertension. Methods and materials In this clinical crossover study, 20 patients with mild to moderate hypertension, treated with long-term beta-blockade, and intermittent claudication or ischemic rest pain, underwent assessment of peripheral circulation before and after 2-week withdrawal of beta-blocking therapy and again 2 weeks after restarting therapy. Replacement therapy (calcium antagonist) was given if considered necessary to control hypertension. Skin microcirculation was assessed with three noninvasive techniques: capillary microscopy of the hallux nailfold, transcutaneous oximetry of the forefoot, and laser Doppler fluxmetry of the great toe.

RESULTS

Mean initial blood pressure was 163/81 mm Hg. Mean heart rate significantly increased with withdrawal of beta-blocker, from 65 bpm to 85 bpm. No significant differences in skin microcirculation and blood pressure were found between measurements obtained before, during, and after withdrawal of beta-blocking therapy. Patients experienced no change in symptoms during the study.

CONCLUSION

beta-Blockers do not appear to have a negative effect on peripheral skin microcirculation and are therefore not contraindicated to treat hypertension when intermittent claudication or ischemic rest pain is also present.

Calcium channel blocker-related periperal edema: can it be resolved?

Calcium channel blocker (CCB)-related edema is quite common in clinical practice and can effectively deter a clinician from continued prescription of these drugs. Its etiology relates to a decrease in arteriolar resistance that goes unmatched in the venous circulation. This disproportionate change in resistance increases hydrostatic pressures in the precapillary circulation and permits fluid shifts into the interstitial compartment. CCB-related edema is more common in women and relates to upright posture, age, and the choice and dose of the CCB. Once present it can be slow to resolve without intervention. A number of strategies exist to treat CCB-related edema, including switching CCB classes, reducing the dosage, and/or adding a known venodilator such as a nitrate, an angiotensin-converting enzyme inhibitor, or an angiotensin-receptor blocker to the treatment regimen. Angiotensin-converting enzyme inhibitors have been best studied in this regard. Diuretics may alter the edema state somewhat, but at the expense of further reducing plasma volume. Traditional measures such as limiting the amount of time that a patient is upright and/or considering use of graduated compression stockings are useful adjunctive therapies. Discontinuing the CCB and switching to an alternative antihypertensive therapy will resolve the edema.

Calcium channel blockers, postural vasoconstriction and dependent oedema in essential hypertension

Treatment with calcium channel blocker (CCB)s, dihydropyridines and others, is frequently complicated by dependent oedema in the absence of sodium retention or cardiac failure, a bothersome side effect of unclear aetiology. The present paper reviews our own and other work dealing with the antagonism exerted by such drugs on postural vasoconstriction, a mechanism triggered by limb venous congestion during orthostasis and controlled through a local sympathetic axo-axonic reflex and increased myogenic tone in response to changes in transmural pressure. By stabilising capillary pressure, postural vasoconstriction counteracts fluid hyperfiltration consequent to gravitational stimuli, and consistent evidence shows attenuation of this response by L-type calcium channel blockers. Interference with the postural reflex control of skin blood flow may therefore contribute to dependent oedema, although cannot entirely explain its development. Attenuation of postural vasoconstriction may amplify the fluid hyperfiltration induced by CCBs through other mechanisms, such as imbalanced intracapillary pressure or enhanced vascular permeability, which are the main factors determining net fluid filtration into the interstitial compartment.

Methods for evaluation of peripheral neurovascular dysfunction

Measurement of skin blood flow is a sensitive marker of C-fiber neurovascular dysfunction. It precedes development of abnormalities in diabetes mellitus, correlates with in vivo indices of the metabolic syndrome, and may be a "benchmark" for future studies on agents to improve microvascular dysfunction in diabetes mellitus. Skin blood flow can be measured under basal and stimulated conditions. There are different methods of evaluation. Iontophoresis and microdialysis are novel methods of drug delivery and the latter may be used as a means of extracting analytes in the skin. Theses methods are not invasive (iontophoresis) or minimally invasive (microdialysis). They can be performed repeatedly and safely in most patients. The use of microdialysis may be limited by sampling only water-soluble molecules. An alternative to microdialysis is iontophoresis, which works better with polar molecules. A combination of microdialysis and iontophoresis techniques can be useful in assessment of the pharmacokinetics of polar and nonpolar agents and the physiology and pathophysiology of the skin neurovascular system.

Ankle Edema Formation during Treatment with the Calcium Channel Blockers Lacidipine and Amlodipine: A Single-centre Study

All studies suggesting a lower incidence of edema on lacidipine than on amlodipine are based on subjective scoring. Therefore, we have compared edema formation on two dihydropyridine calcium channel blockers, using an accurate method for quantitative assessment of foot volume. In a randomized study, we treated 62 patients with essential hypertension for 12 weeks starting with either lacidipine 4 mg o.d. (n = 30) or amlodipine 5 mg o.d. (n = 32). At 6 weeks, the doses were increased to that maximally allowed (lacidipine 6 mg, n = 18; amlodipine 10 mg, n = 12) if trough diastolic blood pressure response was insufficient (>90 mmHg and decrease < 10 mmHg). Edema, scored visually, occurred more frequently (p = 0.02) on amlodipine (15/32) than on lacidipine (6/30); this was confirmed by an increase of foot volume above the 95% upper limit of normal variation in 15 patients on amlodipine and in only five patients on lacidipine (p = 0.01). In the whole group of patients, both the increases of foot volume and the decreases of blood pressure just failed to be significantly different between amlodipine and ]acidipine (foot volume, +3.3+/-1.0% on amlodipine and +1.2+/-0.5% on lacidipine, p = 0.08; mean arterial pressure, -11+/-1% on amlodipine and -8+/-1% on lacidipine, p = 0.052). In patients requiring dose increase, the increase of foot volume on amlodipine was more pronounced (p < 0.05), and the antihypertensive effect was larger (p < 0.05) than on lacidipine. In conclusion, our data show a higher incidence of edema on amlodipine than on lacidipine, which has to be explained at least partly by a comparably higher dose c.q. a larger antihypertensive effect of amlodipine. Other mechanisms might have contributed to these differences and need to be explored.