Dermatology Online Journal

The spectrum of cutaneous reactions associated with calcium antagonists: A review of the literature and the possible etiopathogenic mechanisms
Palamaras Ioulios, Michaelides Charalampos, and Tsele Efrossini
Dermatology Online Journal 9 (5): 6

Dermatology Department, West Attika General Hospital of Athens, Greece. ioulios@hol.gr

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Abstract

Calcium antagonists (CAs) or calcium-channel blockers, are a common group of antihypertensive medications. These drugs have the property of blocking the calcium channels of the vascular and cardiac smooth-muscle fibers. They have been associated with cutaneous reactions ranging from exanthems to severe adverse events. The frequency of these reactions may be as high as 48 percent. The most common are ankle or pedal edema (up to 30 %), gingival hyperplasia (up to 21 %), and flushing (up to 10 %). Less common are facial or truncal telangiectasia, photosensitivity reactions, new-onset psoriasis (as well as exacerbation of it), purpuric exanthems, pemphigoid manifestations, subacute cutaneous lupus erythematosus, gynecomastia, erythromelalgia, and oral ulcers. Particular adverse manifestations relate to drug potency, degree of vasodilatation, patient age, coexistence of other diseases, co-administration of other cytochrome P450 CYP3A-metabolized medications, fibroblast stimulation, and blood cell effects. Calcium antagonists are associated with a wide range of skin reactions, and the dermatologist should include these in the differential diagnosis of cutaneous diseases.

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Introduction

The drugs classified as calcium antagonists (CAs), or calcium-channel blockers (CCBs) are a diverse group of antihypertensive medications introduced into clinical medicine in the 1960s [1]. They possess the property of blocking the transmembrane flow of calcium ions into the cell through voltage-gated channels [1], thus inhibiting the activation of the actin-myosin complex and muscular contraction [2].

At the present time there are six known different calcium-channel subtypes (see table 1) [2]. The L-type has been found in cardiac muscle, vascular smooth muscle (SM) (arterial and venous), nonvascular SM (bronchial, gastrointestinal, genitourinary, uterine), and noncontractile tissues (pancreas, pituitary, adrenal glands, salivary glands, gastric mucosa, white cells, platelets, and lacrimal tissue) [1].

The structure of the voltage-sensitive calcium channel comprises the ion-conduction pore α₁-subunit (through which calcium ions pass) and several accessory subunits designated α₂, β, γ, and δ. Variations in the α₁-subunit account for the differences in voltage and pharmacologic sensitivity between the voltage-sensitive channel subtypes [2]. The α₁-subunit itself contains several different functional regions to which the CAs bind, with CAs of different classes (see below) binding to different regions [1]. The α₂-, β-, γ-, and δ- subunits modulate the function of the α₁-subunit. Regulation of the entire calcium channel itself is a function of catecholamines, angiotensin II, endothelin, and hormones[1].

Pharmacologically, CAs are divided into benzothiazepines (diltiazem), phenylalkylamines (verapamil), dihydropyridines (nifedipine), and tetraols (mibefradil)[2].

The current, most useful classification is the one based on receptor binding properties, tissue selectivity, and pharmacokinetic profiles proposed by Luscher and Cosentino (see table 2) [3].

The CAs, which are currently used for the treatment of hypertension, angina, supraventricular arrhythmias, and in one case for the prevention and short-term therapy of neurological deficits from subarachnoid hemorrhage, are amlodipine besilate, barnidipine, bepridil cilnidipine, diltiazem hydrochloride, efonidipine felodipine, fendilline, isradipine, lacidipine, lercanidipine, mibefiadil, nicardipine nimodipine, nisoldipine, nitrendipine, nifedipine, and nilvadipine. Only diltiazem hydrochloride, verapamil, nifedipine, and nicardipine are available in intravenous formulation.

CAs have also been used in dermatology for the treatment of erythromelalgia (nifedipine extended release-ER, diltiazem) [4], calcinosis in juvenile DM (diltiazem) [5], Raynaud's phenomenon in systemic sclerosis (nifedipine, diltiazem, amlodipine, isradipine, nisoldipine, and felodipine) [6, 7, 8, 9], perniosis (nifedipine) [10], chronic anal fissures (oral or topical use of diltiazem gel) [11], pain relief in postherpetic neuralgia by iontophoresis (nicardipine, verapamil, and diltiazem) [12, 13], keloids (intralesional verapamil) [14], and for the prevention of skin-flap necrosis in rats and rabbits (nifedipine, verapamil [15, 16], nimodipine [17], nitrendipine, and diltiazem [18]) by topical and systemic administration.

Pharmacodynamics

The main effect of CAs is vasodilation with lowering of the blood pressure. Verapamil, gallopamil, diltiazem, bepridil, mibefradil, and monatepil also delay atrioventricular conduction and decrease the myocardial contractility. Several CAs inhibit the growth and proliferation of vascular smooth muscle and fibroblasts. They may also inhibit synthesis of extracellular matrix proteins (collagen, fibronectin, and proteoglycans).

Conversely, nifedipine upregulates keratinocyte growth factor (KGF) secretion and gene transcription by gingival fibroblasts in vitro and KGF mRNA transcripts are elevated in drug-induced gingival hyperplasia in vivo [19]. Likewise, gingival fibroblasts, cultured from patients with gingival overgrowth under treatment with nifedipine or nicardipine, give a better cell-proliferation rate, rate of DNA syntheses, and an increased number of epidermal growth factor (EGF) receptors with the use of nifedipine, diltiazem, and verapamil [20]. CAs also have immunomodulatory and dysregulatory effects; in vitro they depress T-cell function and in vivo produce an immune dysfunction by inhibition of potassium efflux in lymphocytes.

Moreover, verapamil inhibits mast-cell degranulation, platelet aggregation, and neutrophil function by calcium-dependent pathways. In addition, nifedipine decreases platelet aggregation [15].

The main adverse effects are related to their pharmacologic action (vasodilation, negative inotropic, and dromotropic action). The vasodilation produced mainly by the dihydropyridines (especially by the immediate-release preparations) appears to be dose related: headache, dizziness, flushing, and tachycardia may result [2]. Constipation may occur with verapamil in over 25 percent of patients [1]. Gingival hyperplasia and peripheral ankle or pedal edema are two unique side effects of CAs that are discussed below [27].

There are several cutaneous reactions associated with CAs (see table 3a, b). The most frequent are flushing, ankle edema, and gingival hyperplasia. Variations in the bioavailability of these drugs appears to be relevant to the pathogenesis of these effects.

Pharmacokinetics

After oral administration, bioavailability of these drugs varies depending on first-pass metabolism in the intestinal wall and liver. CAs are metabolized to less active metabolites, mainly by cytochrome P-450 CYP3A[1]. Thus, bowel disease, liver disease, or age-associated physiologic atrophy of the intestinal villi (and likewise the attenuation of hepatic metabolism and hepatic flow) could decrease the clearance of the drug and provoke an increased CAs effect [1]. Furthermore, hepatic biotransformation of CAs may be greater in women than men [1].

In diabetic patients, the relative risk of adverse events associated with the use of CAs is greater [21]. There are many different mechanisms implicated, and these mechanisms are discussed below. Moreover, we should not overlook the fact that (a) isoforms of cytochrome CYP450 that may form the reactive metabolite are present in the skin, (b) human cultured keratinocytes are able to bioactivate drugs to their reactive metabolites, (c) the well-known photosensitivity of some drugs suggests that they do reach the cutaneous level after systemic administration, (d) the epidermal keratinocyte is a key cell in the initiation and propagation of cutaneous immune reactions; keratinocyte-derived cytokines provide essential signals for the migration of Langerhans cells, therefore antigen presentation and ultimately T-cell activation, and (e) keratinocytes themselves express human leukocyte antigen (HLA-DR) at inflammatory sites, and may serve as antigen presenting cells (APC) in situations that predispose subjects to cutaneous drug reactions [22].

Methods

Presentation of all the spectrum of cutaneous reactions associated with calcium antagonists and their classification according the active substance and frequency appears in tables 3a and 3b.

Results

Flushing

Flushing is a common side effect, caused by vasodilation. The CAs that may elicit this reaction in order of frequency are nifedipine 10.5-25 percent [23, 24], (the percentage is higher for the immediate-release formulation), nisoldipine 7 percent [23], felodipine 4-7 percent [25], isradipine 6 percent (dose related) [26], lacidipine 5 percent [35], nilvadipine 5.8 percent [23], nitrendipine 4.6 percent [23, 29], cilnidipine 4.5 percent [23], barnidipine 3.4 percent [23], nicardipine 1.8-3 percent [23, 26], manidipine, 2.2-2.7 percent [23, 30, 31], amlodipine 1.2-2 percent [32], efonidipine 1.8 percent [23], lercanidipine 1.1 percent [23], diltiazem 0.1-3 percent [23, 33], verapamil < 1 percent [34].

Ankle or pedal edema

Nonvascular peripheral (ankle or pedal) edema has been reported during treatment with almost all CAs; nifedipine 10-30 percent [27] (nifedipine SR: 1-8 %)[24], verapamil 6 percent [27], diltiazem 6-10 percent [27] (diltiazem SR 2-3 %)[33], felodipine 2-17 percent [25], isradipine 6 percent [26,28], amlodipine 6-15 percent (6 % in males, 15 % in females)[32], lacidipine 4-4.4 percent [35, 36], lercanidipine 1.2-9 percent [36, 37], nicardipine 3 percent [26], nisoldipine 6-19 percent [38], manidipine 4.9-6 percent [30, 31], mibefradil 7 percent [39]. This side effect appears to be dose related for the majority of the above enumerated drugs. Concerning the etiopathogenesis of this phenomenon, several mechanisms have been proposed; stimulation of the renin-angiotensin-aldosterone system, fluid-volume retention [40], and precapillary anteriolar vasodilation [41, 42, 43]. CAs increase the vascular-fluid filtration from the intravascular to the extravascular compartment, by mechanisms probably independent of interference with the modulation (relaxation) of the intrinsic myogenic tone of the precapillary arterioles at the dorsum of the foot. This modulation seems to be dose related with these drugs because the newer calcium-channel-blocking agents develop a lower incidence of edema through a balanced pre- and post-capillary vasodilation [41, 43]. Further studies are needed to elucidate the exact pathogenesis of this reaction.

Gingival hyperplasia

Gingival hyperplasia (GH) can be idiopathic, inherited, or iatrogenic. It is characterized by enlarged and occasionally inflamed gums (the interdental papilla and the free gingival margins increase in size and thickness progressively covering the clinical tooth crowns) [44, 45]. The prevalence of overgrowth with the use of CAs may be as high as 38 percent. The incidence is 3.3-times more common in men than in women [46].

To date, the CAs reported to cause GH are verapamil [44], diltiazem [44], nifedipine [47], felodipine [44], isradipine [44], nitrendipine [45], nimodipine [44], amlodipine [48, 49], nicardipine [44, 50], manidipine [51]. The prevalence of nifedipine may be greater than that of other CAs [46]. The incidence may approach 10 percent [24]. The prevalence of amlodipine-related GH was calculated in 3.3 percent [48]. Amlodipine GH associated with facial telangiectasia have also been described in a 3-year-old girl [49]. With felodipine the onset time was 4 weeks after initiation of the treatment. By experimental studies the GH resulted to be dose and time related [44].

Nicardipine [50], (incidence less than 1 %), induced gingival hyperplasia in a 8.5-year-old boy 2 years after the increase of his daily dose from 40 mg to 50 mg.

Histologically, the gingival tissue exhibits hyperplasia of connective tissue with lymphoplasmacytic inflammatory infiltrate. The surface epithelium is acanthotic with the formation of elongated test-tubelike rete ridges [44, 45]. Ultrastructural studies reveal an overproduction of collagen and fibronectin without a significant increase of the area occupied by fibroblasts [52]. Moreover, nifedipine has been found to affect the inflammatory infiltrate with a greater number of B-lymphocytes [53]. There are several studies that propose the etiopathogenesis of this phenomenon. Brown et al. [45] considered a possible defect in collagen degradation. The CAs decrease the uptake of folic acid, which participates in the production of active collagenase enzyme (that degrades collagen) by influencing Ca++/Na+ flux, therefore they inhibit the catabolism of ground substance in the oral mucosa. Nyska et al. [54] suggested a blockage of the aldosterone synthesis in zona glomerulosa of the adrenal cortex by CAs, with subsequent feedback stimulation of an increase in pituitary secretion of ACTH, which produces hyperplasia of zona glomerulosa and increases the secretion of androgen hormones that may act on the gingival cells and matrix to produce gingival hyperplasia. Young et al. [34] and Van der Vlenten [49], proposed that inflammation and gingivitis secondary to bacterial plaque induce the production of gingival crevicular fluid. This serum-derived transudate may cause accumulation of the CA in the gingivae with subsequent localized toxic effect and gingival hyperplasia.

According to the latest data, several cofactors seem to interact with the CAs and influence the onset and severity of this disorder. First, the absorption of the drug and its blood drug level depends on the age of the patient [1, 2, 55]. Second, the gender of the subject if important; males are three times as likely as females to develop gingival overgrowth [56]. Third, the presence of bacterial plaque and gingival inflammation is a major cofactor [56]. Actually, control of gingival inflammation may produce a significant remission [51]. Under conditions of GH, the sequestration of the drug in the crevicular fluid, is up to 290-fold greater than in plasma [57].

Keratinocyte growth factor (KGF) is upregulated by nifedipine. In fact, KGF mRNA transcripts are elevated in drug-induced GH in vivo, and nifedipine upregulates KGF secretion and gene transcription by gingival fibroblasts in vitro[19]. Moreover, CAs stimulate collagenase synthesis in fibroblasts by altering the fibroblast cell shape, enhancing cell-proliferation rate and DNA syntheses, and increasing the number of EGF-receptors (EGF-RCs) [20, 58]. And androgen metabolism and the overproduction of 5-α-dihydrotestosterone (5-α-DHT) and 4-androstenedione upregulate gingival fibroblast proliferation and stimulate matrix synthesis [59]. In fact, a positive correlation between GH and plasma testosterone was noted in dogs whose castration prevents calcium-channel-blocker induced GH [60]. All these factors interact for the development of gingival hyperplasia (see fig. 1).

Figure 1

The upregulation of KGF stimulates the keratinocytes. Keratinocytes secrete TGF-β₁ [61] (transforming growth factor-β). TGF-β₁ has a central role in GH; it stimulates fibroblasts to increase their synthesis of extracellular matrix proteins (i.e. collagen, fibronectin, and proteoglycans). TGF-β₁ is also bound locally to the extracellular matrix in latent phase and can be activated after injury. TGF-β₁ induces both infiltrating cells and resident cells to produce more of it. This autoinduction amplifies the biological effects of TGF-β₁ and with repeated injury, (i.e., the bacterial plaque and chronic gingivitis), the increase in TGF-β₁ production is sustained. This creates a chronic vicious circle of TGF-β₁ overproduction, which leads to a progressive deposition of extracellular matrix proteins and therefore GH [61]. In addition steroid receptors (such as testosterone receptors), located in the gingivae [60] may act as post-transcriptional regulators for genes of different isoforms of TGF-β₁ [61].

Furthermore, TGF-β increases the formation of the biologically effective androgen metabolite 5-α-DHT from testosterone, thus increases the connective-tissue turnover [62]. Moreover, it was found that nifedipine elevates 5-α-DHT and 4-androstenedione metabolism by 24-fold and 32-fold, respectively, in hyperplastic gingival tissue [63]. IL-α stimulates DHT and androstenedione synthesis by 2-fold and EGF, stimulates DHT by 2-fold and testosterone by 5-fold [64]. The importance of these interactions may be seen in the healthy female gingival tissue that normally does not metabolize testosterone significantly. However, in the presence of gingival inflammation, 5-α-DHT formation is comparable to that of male samples [63]. Considering this mechanism, it seems plausible that GH can be likened to the clinical manifestation of a keloid formation in gingival tissue.

Facial telangiectasia

Photodistributed facial telangiectasia has been described for nifedipine [47, 65], felodipine [66], amlodipine [49, 67, 68], and diltiazem [66]. Clinically it is characterized by marked arborizing telangiectasia spreading on all the photoexposed areas of the body: face (more frequently), upper back, shoulders, and extensor aspects of the upper arms, and chest) [68].

Nifedipine-induced telangiectasia was first reported by Tsele et al. [65]. The slow-release formulation is responsible for this effect. There is no gender preference and the onset time is 4-8 months after the initiation of therapy. Usually, within 3-9 months after discontinuation of the drug the telangiectasia is resolving, with gradual dramatic improvement [69]. Felodipine-induced facial telangiectasia is also reported [66]. A considerable improvement was seen 2 months after stopping the drug. With amlodipine [67, 68], the onset of the eruption occurs at up to 12 months, and the remission begins 3 months after withdrawal of the drug, with complete resolution after 6 months.

The etiology of this disorder is not fully understood. Several mechanisms have been postulated: (1) Both the vasodilatory action of the CA and the actinic damage produced in the vessels in photoexposed areas may contribute to this phenomenon [66]. (2) Underlying longstanding untreated rosacea may also be an important factor [66]. (3) Alternatively, it may be an idiosyncratic reaction [69]. (4) An abnormal sensitivity to ultraviolet (UVB and UVA) wave-lengths could generate toxic photoproducts [70]. However, only in vitro and at higher plasma levels (unattainable in vivo), UVA irradiation induces formation of toxic photoproducts by nifedipine [69]. Furthermore, phototesting in vivo has failed to produce consistent results [69]. In addition, photostability and phototoxicity studies with diltiazem have shown that the main photoproduct was diltiazem-S-oxide and the latter was neither mutagenic nor toxic [71]. On the other hand, drug-induced photosensitivity by diltiazem demonstrated a better minimal-erythema-dose response in the UVB region [72].

Telangiectasia related to CAs has also been described on nonphotoexposed areas [73]. Spiderlike telangiectasias were present on the trunk of a 70-year-old woman who had been taking felodipine for several years. Except hypertension, the patient had no other accompanying diseases. It should be emphasized that complete resolution of these lesions was not achieved on stopping the drug. The underlying mechanism remains to be elucidated, but it has been postulated that it might have been resulted by felodipine's chronic vasodilation.

Photosensitivity reactions

These reactions are manifested as generalized or localized erythema or maculopapular rash on the face and upper trunk. They may be induced by nifedipine and diltiazem [47], and there may be a cross-reaction between these agents [74]. The onset time was 5 months after initiating nifedipine and 1 week after diltiazem (on the same patient). Complete clearing occurred within 3 weeks after discontinuation of nifedipine and 1 week after diltiazem. The exact mechanism is still unknown but the perivascular infiltration with mononuclear cells suggests participation of the reticular immune system. It is possible that an antigen formed by a photoreactive drug or metabolite (such as diltiazem-s-oxide [58]) binds to skin proteins and leads to a UV-dependent delayed-hypersensitivity reaction.

A photodistributed hyperpigmentation has been observed in African-American females under treatment with Diltiazem sustained release [75, 76]. Physical examination showed blue-gray reticulated hyperpigmented macules and patches on the photoexposed areas, usually of the upper trunk. The areas involved in order of frequency are face, neck, chest, forearms, and hands. Histologically the changes described consistent of a lichenoid dermatitis with basal vacuolar alteration and prominent pigment incontinence (i.e., lichenoid drug eruption). There are five reported cases of this disorder; In four, the mean duration of diltiazem administration prior to the onset of hyperpigmentation was 8 months. In the fifth case it was 5 years. Over a 50 percent improvement was noticed at 10 months after stopping the drug. UVA is proposed to be a causal agent, and a metabolite may represent the photosensitizer [75].

Other lichenoid eruptions such as lichenoid purpura and widespread lichen planus are described with diltiazem hydrochloride [77] and amlodipine [78], respectively. The first case [77] refers to a 65-year-old male who presented pruritic, purpuric lichenoid papules on his legs and buttocks, 1 month after initiating treatment with diltiazem. Histologically, a lichenoid infiltration of lymphocytes and histiocytes was found into the dermoepidermal junction. A complete remission of the dermatitis was observed 3 weeks after the change of diltiazem. The pathogenic process of lichenoid purpura is believed to be related to immunological events. Diltiazem itself may have played an immunological role (see also pharmacodynamics). The second case [78] is of a 56-year-old female who presented a widespread intensely pruritic lichenoid eruption consisting of violaceous plaques and pigmented macules over the limbs, and the anterior and posterior trunk, two weeks after starting treatment with amlodipine. Wickham striae were also detectable in the oral cavity. There was a significant improvement of the clinical findings, 5 weeks after discontinuation of amlodipine and simultaneous administration of oral acitretin 30 mg daily, oral antihistamines and potent topical corticosteroids.

Psoriasiform eruptions

These eruptions are associated with diltiazem and nifedipine [47]; new-onset psoriasis as well as exacerbations of it, are associated not only with diltiazem [79] and nifedipine [80] but also with felodipine [80] and amlodipine [80]. The median latent period between the precipitation or exacerbation of psoriasis and the beginning of intake of CAs is 28 months. The mean age is 64.1±8.9 years and the male-female ratio is 2.25. Almost half, of the patients are also taking β blockers (the latter as well may cause psoriasis).

There are several presumed mechanisms:

• CAs enhance keratinocyte proliferation and differentiation, which depend on intracellular calcium levels [81, 82].
• β blockers likewise provoke a derangement in calcium metabolism by blocking the calcium influx into the cells; hence, the simultaneous intake of CAs might have a synergistic effect on the onset of psoriasis [80].
• Nifedipine was discovered to inhibit a final event in the cornification of epidermal cells (specifically, the processing of profilaggrin to filaggrin) by blocking the calcium influx into them [80].

Acute generalized exanthematous pustulosis AGEP)

This reaction is associated with acute, extensive formation of sterile pustules, fever (> 38° C) and peripheral blood leukocytosis has been reported with extended-release diltiazem [83, 84] and nifedipine [85]. The clinical and pathological findings are similar to those of pustular psoriasis. The onset time varied from 10-14 days and the eruption improved within 1 week after discontinuation of the drug. Regarding extended-release diltiazem, the patch testing was positive at 2 days.

The etiology remains obscure, however, it is possible that immune-mediated mechanisms may promote the release of potent neutrophil chemoattractants and activators, such as interleukins (ILs) and tumor necrosis factor-α (TNF-α). These mechanisms therefore could be triggered by the CAs or their metabolites, particularly in genetically susceptible individuals [83].

Hypersensitivity syndrome

This type of reaction may be a special risk for patients with psoriasis and concomitant intake of diltiazem [86]. The hypersensitivity syndrome reaction induced by this drug may present not only as an exfoliative dermatitis (rate, cases per million prescriptions = 0.63), but also as a severe toxic epidermal necrolysis (TEN) (rate, cases per million prescriptions = 0.09). CA-induced TEN is characterized by fever and internal organ involvement (hepatic injury, pulmonary, hematologic or renal impairment, and thyroid dysfunction) [79]. Often there is early atypical lymphocytosis and later eosinophilia. The onset of the eruptions varies from 2 to 10 days after initiation of the drug [47]. The etiology of this phenomenon is unknown, but it is supposed to represent an idiosyncratic reaction [86].

Exfoliative dermatitis and Stevens-Johnson-Syndrome/TEN

Exfoliative dermatitis was described with verapamil [79] (rates, cases per million prescriptions = 0.1) and nifedipine [79] (rate = 0.42). Thus, we can observe comparable rates for nifedipine and diltiazem but only a single report cited for verapamil.

Severe adverse reactions such as erythema multiforme (EM), and Stevens-Johnson syndrome (SJS), have been reported with verapamil [79] (rate, cases per million prescriptions=0.21 and 0.65 respectively), diltiazem [79] (0.44 and 0.27), nifedipine [79] (0.07 and 0.15), and amlodipine [87], either with primary treatment or following substitution for nifedipine. As a result, the rate of SJS, TEN (combined), and EM was nearly identical for diltiazem and verapamil [79]. The average age of patients was 64 years. In EM and SJS, the time from initiating medication to reaction onset averaged from 2 days to 3 months [79,88]. With verapamil, the resolution began approximately 4 days after discontinuation of the drug [89].

The underlying mechanisms remain unclear, but it has been proposed that these drugs may be able to form sensitizing haptens [87].

Subacute cutaneous lupus erythematosus (SCLE).

This form of lupus has been associated with verapamil, diltiazem, and nifedipine [90]. The mean patient age was 67 (from 48 to 86 years) and the female-male ratio: 3.5. The time from starting the medication to onset reaction varied from 6 months to 5 years. As to the nine patients reported, 78 percent were antinuclear-antibody (ANA) positive, and 89 percent were anti-Ro- (SSA) or anti-La- (SSB) antibody positive. Two patients had evidence of concomitant or preexisting connective-tissue disease. Complete resolution was observed within 2-12 weeks of drug cessation. ANAs were reduced, but anti-Ro and anti-La remained positive.

As for the etiology, it has been postulated a two-fold mechanism. First, CAs may induce a Ro and La antigen displacement to the surface of the keratinocyte by altering the cytosolic calcium concentration [90, 91, 92]. Second, they provoke a perturbation of lymphocyte function that could create an immunologic environment and therefore allow the emergence of autoantibodies [93, 94, 95]. These may bind to Ro and La antigens and result in keratinocyte injury by complement-mediated lysis and antibody-dependent cellular cytotoxicity (ADCC), similarly in the manner proposed for idiopathic SCLE [96, 97].

Pemphigus and pemphigoid

Pemphigus foliaceous and pemphigoid nodularis have been described with nifedipine [98]. The latter was presented on a 70-year-old male after 3 months of nifedipine 10 mg daily. On physical examination there was evidence of pruritic papules and nodules initially on the upper back and afterward on the trunk, limbs, face, and scalp. Ulceration, which healed without scarring, was present only in the mouth. In addition, involvement of the nail beds of several fingers and toes resulted in the formation of pterygium unguis.

The finding of the skin biopsy and direct immunofluorescence (IMF), supported the diagnosis of nodular pemphigoid. Furthermore, circulating antibodies anti-basement membrane zone (BMZ) staining with IgG and C3 were detected to a titer 1:800 by indirect IMF. Moreover, antibodies to the 230-kDa pemphigoid antigen were found by Western blot. With the cessation of nifedipine, the patient's skin showed considerable improvement, together with a fall in indirect IMF titer to 1:100.

There are several theories that try to explain the etiopathogenesis of drug-induced pemphigoid. Some authors believe that drugs may bind in the lamina lucida and act as haptens inducing the formation of anti-basement-membrane-zone antibodies [99]. Others suggested that drugs may structurally modify molecules and uncover hidden epitopes, thereby stimulating an autoimmune response [100]. It is presumed that skin susceptibility to nifedipine might be genetically determined, with some nifedipine-treated patients developing an acantholytic reaction and others a subepidermal bullous eruption [101].

Erythromelalgia

This reaction has been related to nifedipine [79], diltiazem [47], verapamil [102], and nicardipine [103]. On the other hand, nifedipine extended release and diltiazem have also been used for its treatment [104].

There are three subtypes of erythromelalgia: (a) thrombocytosis and hyperviscosity, (b) microvascular ischemia (vasoconstrictive-reactive hyperemia), which is the most frequent and (c) vasodilatory [105]. Regarding the calcium-channel-blocker-induced erythromelalgia the time lapse between the first dose of the drug and its occurrence varied from 8 weeks to 1 year: the time from discontinuation of the drug to resolution ranged from 1 to 14 days [102]. All blood exams including ANA, rheumatoid factor and a general antoantibody screening resulted negative [102]. This drug-induced erythromelalgia may represent a manifestation of the third subtype (vasodilatory). However, the exact mechanism remains unknown.

Nifedipine and diltiazem may have a therapeutic effect on the second subtype of erythromelalgia, by attenuating the vasoconstriction phase and improving the nutritional capillary flow (by relaxing the precapillary's sphincters)[104, 106, 107].

Gynecomastia

Breast enlargement has been associated with diltiazem [108], verapamil [109], nifedipine [109], and amlodipine [110].

Regarding the etiopathogenesis, two different mechanisms have been proposed: First, verapamil, (the oral formulations), but not dihydropyridine and benzothiazepine CAs may raise serum PRL concentrations [111, 112, 113, 114]. In fact the prevalence of hyperprolactinemia was found to be 8.5 percent. There is an enhancement of PRL secretion possibly resulting from decreasing the hypothalamic generation of dopamine [113]. Moreover testosterone levels were lower in patients on verapamil [111]. Thus, a possible mechanism could be the suppression of gonadotropin-releasing hormone/ thyrotropin-releasing hormone (GnRH/TRH), which stimulates anterior-pituitary hormone secretion of luteinizing hormone (LH), hence the decrease of testosterone's synthesis [115].

Another mechanism might be the decreased cytochrome P450 CYP3A activity produced by CAs (verapamil and diltiazem) [1]. Apparently, there is an increase in serum estradiol concentration by inhibiting cytochrome P450 CYP3A-dependent neutralization of estradiol [116, 117]. This increase results in an increment of PRL secretion proportionate to the degree of estrogenization [118].

Oral ulcers

Ulcers of the oral mucosa have been attributed to verapamil and diltiazem [119]. Clinically they appear as non-indurated extremely painful ulcers with a central erythematous zone and a white halo, situated on the lateral borders of the tongue. They are recalcitrant to any known therapeutic intervention. For diltiazem and verapamil the onset time is 5 months and 1 year, respectively, after the initiation of the treatment. A complete healing of the ulcers occurred from 2 weeks to 1 month after discontinuation of the drugs.

The results of the histopathologic examinations are nonspecific: spongiosis, foci of necrosis, and a mixed (lymphocytes and plasma cell) inflammatory-cell infiltrate. The pathogenesis of drug-induced ulceration is related to immunological or nonimmunological mechanisms. In the immunological route, the drug or any of its components may trigger an immune response, which generates an exaggerated reaction directed at the surface epithelium resulting in ulcers. In the nonimmunological route, the drug may directly stimulate mast cells and lymphocytes to release cytotoxic chemical mediators.

Conclusions

This article represents our views regarding the dermatological adverse reactions related to CAs, after a comprehensive review of the published literature. We have attempted to present an unbiased summary of the available data and point out that the dermatologist should be aware of these reactions during the process of differential diagnosis for skin diseases.

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