The efficacy and safety of tacrolimus ointment: a clinical review

Dual effect of tacrolimus on mast cell-mediated allergy and inflammation through Mas-related G protein-coupled receptor X2

BACKGROUND

Topical tacrolimus, although widely used in the treatment of dermatoses, presents with an immediate irritation on initial application resembling a pseudo-allergic reaction. Mas-related G protein-coupled receptor X2 (MRGPRX2) in mast cells (MCs) mediates drug-induced pseudo-allergic reaction and immunoglobulin E (IgE)-independent pruritis in chronic skin diseases. However, the immunosuppression mechanism of tacrolimus on MCs via MRGPRX2 has not been reported.

OBJECTIVE

To investigate the role of MRGPRX2 and the mechanism of action of tacrolimus on its short-term and long-term applications.

METHODS

Wild-type mice, KitW-sh/W-sh mice, and MrgprB2-deficient (MUT) mice were used to study the effect of tacrolimus on in vivo anaphylaxis model. LAD2 cells and MRGPRX2-knockdown LAD2 cells were specifically used to derive the associated mechanism of the tacrolimus effect.

RESULTS

Short-term application of tacrolimus triggers IgE-independent activation of MCs via MRGPRX2/B2 in both in vivo and in vitro experiments. Tacrolimus binds to MRGPRX2, which was verified by fluorescently labeled tacrolimus in cells. On long-term treatment with tacrolimus, the initial allergic reaction fades away corresponding with the downregulation of MRGPRX2, which leads to decreased release of inflammatory cytokines (P < 0.05 to P < 0.001).

CONCLUSION

Short-term treatment with tacrolimus induces pseudo-allergic reaction via MRGPRX2/B2 in MCs, whereas long-term treatment downregulates expression of MRGPRX2/B2, which may contribute to its potent immunosuppressive effect in the treatment of various skin diseases.

Tacrolimus nanocrystals microneedle patch for plaque psoriasis

Plaque psoriasis is characterized by an abnormal thickening of the epidermis, which causes great difficulties for traditional topical drug delivery. Microneedles can pierce the thickened epidermis and deliver drugs to the skin for psoriasis treatment. Tacrolimus is a poorly water-soluble immunosuppressant used for the treatment of psoriasis. In this study, tacrolimus (TAC) nanocrystals (NCs) were produced using a bottom-up technique that dispersed TAC into a sodium hyaluronate-based microneedle patch (MNP), and its therapeutic efficacy was evaluated. The average particle size of the TAC NCs was 259.6 ± 2.3 nm. The mechanical strength of the microneedles was 0.41 ± 0.06 N/needle, which was sufficient to penetrate psoriatic skin. Microneedles were detached from the substrate 10 min after insertion into the psoriasis skin with an insertion depth of 258.8 ± 14.4 μm. The intradermal retention of the MNP (8.40 ± 0.33 μg/cm²) was six times that of the commercial ointment (1.40 ± 0.12 μg/cm²). In pharmacodynamic experiments, results indicated improvement in the phenotypic and histopathological features and reduction in the level of TNF-α, IL-17A, and IL-23 of psoriatic skin treated with TAC NCs MNP. Therefore, MNP loaded with TAC NCs may be a promising approach for psoriasis treatment.

Recent advances in the management of non-infectious posterior uveitis

PURPOSE

To review the current regimens and novel therapeutic modalities in various stages of research and development for the management of non-infectious posterior uveitis (NIPU).

METHODS

We performed a thorough review of current literature using PubMed, Google Scholar and Clinicaltrials.gov to identify the published literature about the available therapeutics and novel drugs/therapies in different stages of clinical trials.

RESULTS

The current management regimen for non-infectious posterior uveitis includes corticosteroids, immunomodulatory therapies and anti-metabolites. However, NIPU requires long-term management for efficacious remission of the disease and to prevent disease relapse. Long-term safety issues associated with steroids have led to efforts to develop novel therapeutic agents including biological response modulators and immunosuppressants. The current therapeutic agents in various stages of development include calcineurin inhibitors, biologic response modifiers and a more a comprehensive modalities like ocular gene therapy as well as novel drug delivery mechanisms for higher bioavailability to the target tissues, with minimal systemic effects.

CONCLUSION

Novel efficacious therapeutic modalities under development will help overcome the challenges associated with the traditional therapeutic agents.

The Effect of Topical Tacrolimus on Pedicled Flap Survival

PURPOSE

Skin necrosis is a known postoperative complication of mastectomies. The pathophysiology of tissue necrosis involves lymphatic congestion, followed by venous congestion and ultimately arterial insufficiency. Recent mouse model studies have shown topical tacrolimus to increase growth of lymphatic collateral vessels and decrease lymphedema, potentially obviating the cycle of necrosis and increasing skin survival. The purpose of this study was to investigate the effect of topical tacrolimus on skin flap necrosis in a rat model.

METHODS

A cranially based dorsal skin flap measuring 3 × 10 cm was raised and reinset on 22 Sprague-Dawley rats. They were then randomized to either the control (topical petroleum jelly) or the treatment (topical 0.1% tacrolimus) arm. In addition, 0.2 g of either ointment was spread over the flap and then covered with an occlusive dressing. Dressings were changed daily with reapplication of both the topical ointment and occlusive dressing. The rats were sacrificed 7 days postoperatively; areas of viable tissue, reversible ischemia, and full thickness necrosis were measured with Fiji software, and comparative analysis was performed with GraphPad statistical software.

RESULTS

The average area of the dorsal flaps in the control and tacrolimus groups was 22.5 and 23.9 cm, respectively. In the control cohort, the average viable area was 42.4%, the average reversible ischemia area was 43.6%, and the average necrotic area was 13.9%. In the tacrolimus cohort, the average viable area was 31.5%, the average reversible ischemia area was 59.3%, and the average necrotic area was 9.2%. Total necrotic area was significantly lower in rats receiving topical tacrolimus as compared with controls (P = 0.015). Furthermore, the ratios of necrotic to reversible ischemia and necrotic to viable tissue were significantly lower in the tacrolimus group as compared with controls (P = 0.003, P = 0.015). There was one incidence of wound dehiscence secondary to rodent self-removal of dressings and suture that required reoperation and reinset.

CONCLUSIONS

Topical tacrolimus was associated with significantly less full thickness necrosis as compared with topical.

No evidence of increased cancer incidence in children using topical tacrolimus for atopic dermatitis

BACKGROUND

Long-term safety of topical calcineurin inhibitors is not well understood. APPLES (A Prospective Pediatric Longitudinal Evaluation to Assess the Long-Term Safety of Tacrolimus Ointment for the Treatment of Atopic Dermatitis; NCT00475605) examined incidence of lymphoma and other cancers in a pediatric population with atopic dermatitis.

OBJECTIVE

To quantify incident malignancies during 10 years in children with atopic dermatitis who used topical tacrolimus for ≥6 weeks.

METHODS

Standardized incidence ratios for cancer events were analyzed relative to sex-, age-, and race-matched control data from national cancer registries.

RESULTS

There were 7954 eligible patients enrolled at 314 sites in 9 countries. During 44,629 person-years, 6 confirmed incident cancers occurred (standardized incidence ratio, 1.01; 95% confidence interval, 0.37-2.20). No lymphomas occurred.

LIMITATIONS

Observational prospective cohort study.

CONCLUSION

The cancer incidence was as expected, given matched background data. This finding provides no support for the hypothesis that topical tacrolimus increases long-term cancer risk in children with atopic dermatitis.

Comparison of anti-atopic dermatitis activities between DHMEQ and tacrolimus ointments in mouse model without stratum corneum

This study is aimed to further investigate the anti-atopic dermatitis (AD) activities of dehydroxymethylepoxyquinomicin (DHMEQ) ointment and compare its effect with that of tacrolimus ointment based on the previous study that DHMEQ improves AD-like lesions. AD were induced by 2,4-dinitroclilorobenzene/oxazolone (DNCB/OX) repeatedly on the ears of BABL/C mice while medical tape was additionally used to disrupt stratum corneum in order to exacerbate the lesions. The mice were randomly divided into groups, which are normal, vehicle, DHMEQ (0.1%) and tacrolimus (0.1%). Those in the last two groups were externally applied with DHMEQ ointment and tacrolimus ointment, respectively. The results showed that both of them significantly improved dermatitis symptoms of DNCB/OX-induced AD-like lesions, such as redness, itching, weeping, scaling and thickening of the skin, while reducing epidermis thickness, dermis thickness and the number of mast cells as well, which were examined histopathologically. In contrast with DHMEQ, tacrolimus led to a significant decrease in body weight after long-term application. Both DHMEQ and tacrolimus suppress DNCB-induced increase of serum total IgE and attenuate expression of inflammatory factors IL-4, IL-6, IL-13, IL-1β and interferon (IFN)-γ in the disrupted ear tissues. On the other hand, the mice applied with tacrolimus became obviously irritable, jumping up and down, and inflammatory exudation on the lesioned-skin surface of the mice was remarkably observed. Contrary to the side effects made by tacrolimus, DHMEQ didn't cause any adverse stimulus response. As a conclusion, DHMEQ is safer, milder and more suitable for long-term use than tacrolimus for the treatment of AD-like lesions.

The Immunosuppressant Macrolide Tacrolimus Activates Cold-Sensing TRPM8 Channels

TRPM8 is a polymodal, nonselective cation channel activated by cold temperature and cooling agents that plays a critical role in the detection of environmental cold. We found that TRPM8 is a pharmacological target of tacrolimus (FK506), a macrolide immunosuppressant with several clinical uses, including the treatment of organ rejection following transplants, treatment of atopic dermatitis, and dry eye disease. Tacrolimus is an inhibitor of the phosphatase calcineurin, an action shared with cyclosporine. Tacrolimus activates TRPM8 channels in different species, including humans, and sensitizes their response to cold temperature by inducing a leftward shift in the voltage-dependent activation curve. The effects of tacrolimus on purified TRPM8 in lipid bilayers demonstrates conclusively that it has a direct gating effect. Moreover, the lack of effect of cyclosporine rules out the canonical signaling pathway involving the phosphatase calcineurin. Menthol (TRPM8-Y745H)- and icilin (TRPM8-N799A)-insensitive mutants were also activated by tacrolimus, suggesting a different binding site. In cultured mouse DRG neurons, tacrolimus evokes an increase in intracellular calcium almost exclusively in cold-sensitive neurons, and these responses were drastically blunted in Trpm8 KO mice or after the application of TRPM8 antagonists. Cutaneous and corneal cold thermoreceptor endings are also activated by tacrolimus, and tacrolimus solutions trigger blinking and cold-evoked behaviors. Together, our results identify TRPM8 channels in sensory neurons as molecular targets of the immunosuppressant tacrolimus. The actions of tacrolimus on TRPM8 resemble those of menthol but likely involve interactions with other channel residues.SIGNIFICANCE STATEMENT TRPM8 is a polymodal TRP channel involved in cold temperature sensing, thermoregulation, and cold pain. TRPM8 is also involved in the pathophysiology of dry eye disease, and TRPM8 activation has antiallodynic and antipruritic effects, making it a prime therapeutic target in several cutaneous and neural diseases. We report the direct agonist effect of tacrolimus, a potent natural immunosuppressant with multiple clinical applications, on TRPM8 activity. This interaction represents a novel neuroimmune interface. The identification of a clinically approved drug with agonist activity on TRPM8 channels could be used experimentally to probe the function of TRPM8 in humans. Our findings may explain some of the sensory and anti-inflammatory effects described for this drug in the skin and the eye surface.

Synthesis of poly(lactide-co-glycerol) as a biodegradable and biocompatible polymer with high loading capacity for dermal drug delivery

Due to the low cutaneous bioavailability of tacrolimus (TAC), penetration enhancers are used to improve its penetration into the skin. However, poor loading capacity, non-biodegradability, toxicity, and in some cases inefficient skin penetration are challenging issues that hamper their applications for the dermal TAC delivery. Here we present poly(lactide-co-glycerol) (PLG) as a water soluble, biodegradable, and biocompatible TAC-carrier with high loading capacity (14.5% w/w for TAC) and high drug delivery efficiencies into the skin. PLG was synthesized by cationic ring-opening copolymerization of a mixture of glycidol and lactide and showed 35 nm and 300 nm average sizes in aqueous solutions before and after loading of TAC, respectively. Delivery experiments on human skin, quantified by fluorescence microscopy and LC-MS/MS, showed a high ability for PLG to deposit Nile red and TAC into the stratum corneum and viable epidermis of skin in comparison with Protopic® (0.03% w/w, TAC ointment). The cutaneous distribution profile of delivered TAC proved that 80%, 16%, and 4% of the cutaneous drug level was deposited in the stratum corneum, viable epidermis, and upper dermis, respectively. TAC delivered by PLG was able to efficiently decrease the IL-2 and TSLP expressions in human skin models. Taking advantage of the excellent physicochemical and biological properties of PLG, it can be used for efficient dermal TAC delivery and potential treatment of inflammatory skin diseases.

Topical tacrolimus in anterior segment inflammatory disorders

Immune mediated inflammatory anterior segment diseases are variable and their management requires intense immunosuppression. Treatment with topical steroids is associated with serious ocular side effects. In order to overcome the potentially blinding complications of topical steroids, immunomodulatory drugs are being used more frequently. Tacrolimus is a calcineurin inhibitor that induces suppression of T lymphocytes activity and reduction of ocular inflammation. Tacrolimus was recently investigated for application in various anterior segment inflammatory disorders. In this review, we will discuss the therapeutic application of topical tacrolimus as a steroid-sparing agent in treating T cell mediated anterior segment inflammation.

15 year experience of tacrolimus application in medical practice

The review presents modern literature data on the use of tacrolimus in medical practice. The results of national and international research on the effectiveness and safety of the drug at various dermatoses are presented.

In vitro Permeability of Intact and De-Epithelialised, Human Vaginal Mucosa to Tacrolimus and Cyclosporin A

Immunosuppressants may be applied topically to mucosal surfaces for treating inflammatory diseases, e.g. vulvar lichen planus and Behçet's disease. The efficacy of the treatment is dependent on the potency of the drug and its penetration into the tissue. In this study the in vitro diffusion characteristics of Tacrolimus (Tac) and Cyclosporin A (CsA) across human vaginal mucosa are investigated and compared. Fresh human vaginal mucosa was snap-frozen in liquid nitrogen and stored at −85 °C. Prior to an experiment, the tissue was defrosted to 20°C in PBS buffer, pH 7.4, and placed in the seven flow cells of a flow-through perfusion apparatus. Either tritiated Tac, or CsA, was then pipetted into the donor chamber of the flow cell. Samples from each flow cell were collected every 2 hours (1.5 ml/h) over a 24-hour period. Statistical analyses were carried out using an F-test. CsA and Tac flux values progressively increased throughout the 24-hour period, and steady state was not reached for either drug. The mean estimated flux values (mean at 16, 20 and 24 h) for Tac (599 ± 44 dpm.cm−2.min−1) were greater than those for CsA (96 ± 5.0 dpm. cm−2.min−1). Whole curve comparison indicated statistically significant differences (P = 1.77×10−163). Both drugs diffuse well across vaginal mucosa. However, mean steady state flux values for Tac were approximately 6 times higher than those for CsA, indicating that human vaginal mucosa is less permeable to CsA than to Tac.

Topical corticosteroids and hospital length of stay in children with eczema herpeticum

There is concern that the use of topical corticosteroids in patients with eczema herpeticum may facilitate dissemination of herpes simplex virus and worsen disease. Our primary aim therefore was to determine whether topical corticosteroid use in children hospitalized with eczema herpeticum is associated with longer hospital length of stay (LOS). We performed a multicenter retrospective cohort study of 1,331 children ages 2 months to 17 years admitted with a diagnosis of eczema herpeticum between January 1, 2001, and March 31, 2010, to 42 tertiary care children's hospitals in the Pediatric Health Information System database. Multivariable linear regression models determined the association between receipt of topical corticosteroid therapy on the first day of hospitalization and the main outcome measure: LOS. Receipt of topical corticosteroid therapy on day 1 of hospitalization was not associated with a longer LOS on unadjusted or multivariable analysis (p = 0.75). Receipt of topical calcineurin inhibitors during the hospitalization was also not associated with a longer LOS (p = 0.12). Receipt of systemic corticosteroids was associated with an 18% adjusted longer LOS (95% confidence interval 2%-36%; p = 0.03). Further study is needed to identify which children with eczema herpeticum may benefit from topical corticosteroids, but their use during active infection is not associated with poorer outcomes, although the use of systemic corticosteroids was associated with a longer LOS and should be avoided in patients with eczema herpeticum pending future prospective study.

Blood level of tacrolimus in patients with severe allergic conjunctivitis treated by 0.1% tacrolimus ophthalmic suspension

BACKGROUND

To estimate the efficacy and safety of 0.1% tacrolimus ophthalmic suspension based on the blood level of tacrolimus in patients with severe allergic conjunctivitis.

METHODS

Fifty-two patients in whom topical anti-allergic agents had been ineffective were treated with 0.1% tacrolimus ophthalmic suspension twice daily for 12 weeks. Adverse drug reactions were monitored, as well as ocular symptoms and signs. The blood concentration of tacrolimus was measured before the initiation of treatment and 4 and 12 weeks later.

RESULTS

About 75% of the patients without concomitant using of tacrolimus ointment had blood levels of tacrolimus below the detection limit of the assay (0.5ng/mL). On the other hand, 71% (week 4) and 57% (week 12) of patients with concomitant using of tacrolimus ointment had blood levels above the detection limit of the assay. However, the maximum blood concentration was less than 2ng/mL. Adverse drug reactions occurred in 16 patients. These were disorders of the eye such as warmness, irritation, and a burning sensation. However, all of the patients could continue treatment with tacrolimus for 12 weeks. There were no serious adverse events such as increased intraocular pressure or ocular infection during the study. All symptoms and signs improved over time.

CONCLUSIONS

The good safety profile of 0.1% tacrolimus ophthalmic suspension based on the low blood concentration of tacrolimus, coupled with demonstrated efficacy, make it an important tool for treating severe allergic conjunctivitis.

Tacrolimus-induced rosacea-like dermatitis: a clinical analysis of 16 cases associated with tacrolimus ointment application

BACKGROUND

Recently, reports have indicated that the continuous use of topical calcineurin inhibitors such as tacrolimus may induce rosacea-like dermatitis (RD).

OBJECTIVE AND METHODS

To assess clinical features of RD associated with tacrolimus, 44 cases of patients diagnosed with RD between 2005 and 2010 at our hospital were retrospectively reviewed.

RESULTS

In total, 22 cases were caused by topical steroid use, 8 by topical tacrolimus use, and 8 by consecutive treatment with topical steroids and tacrolimus. Clinical presentation was basically similar among the 3 groups, although the nose was less frequently affected and pustules were rarely observed in the latter 2 sets of cases. Demodex mites were often found in smears of skin lesions from patients with RD caused by steroids and tacrolimus. Treatment with topical metronidazole was effective in most RD patients.

CONCLUSION

Topical tacrolimus is becoming an important cause of RD along with topical steroids.

Topical delivery for the treatment of psoriasis

IMPORTANCE OF THE FIELD

Psoriasis is one of the most common human skin diseases. Topical therapy forms the cornerstone in the management of mild-to-moderate psoriasis. Topical therapies are also used as adjunctive to systemic therapy in moderate and severe forms of the disease.

AREAS COVERED IN THIS REVIEW

In this review, an overview of psoriasis pathogenesis, new topical medications for psoriasis, new targets and molecules, combination topical therapies and combination of topical and phototherapy is provided. Over the past decade several efficacious and acceptable treatment options have emerged from the age-old therapies. The development of sophisticated formulation options has led to an enhancement in the rate and extent of drug delivery across the skin, increasing therapeutic value and improving patient compliance.

WHAT THE READER WILL GAIN

Readers will learn about monotherapy and combination topical products as well as new topical drug delivery technology to achieve optimal clinical outcomes. This review will highlight the need to generate more dermal pharmacokinetic data for better understanding of the impact of formulation change on skin pharmacokinetics to help design improved topical drug delivery systems.

TAKE HOME MESSAGE

New topical formulations have the potential to achieve better efficacy with improved safety profile.

Update on the management of chronic eczema: new approaches and emerging treatment options

Atopic dermatitis (AD) is a common disease with worldwide prevalence, affecting up to 20% of children and 3% of adults. Recent evidence regarding pathogenesis has implicated epidermal barrier defects deriving from filagrin mutations with resulting secondary inflammation. In this report, the authors comprehensively review the literature on atopic dermatitis therapy, including topical and systemic options. Most cases of AD will benefit from emollients to enhance the barrier function of skin. Topical corticosteroids are first-line therapy for most cases of AD. Topical calcineurin inhibitors (tacrolimus ointment, pimecrolimus cream) are considered second line therapy. Several novel barrier-enhancing prescription creams are also available. Moderate to severe cases inadequately controlled with topical therapy may require phototherapy or systemic therapy. The most commonly employed phototherapy modalites are narrow-band UVB, broadband UVB, and UVA1. Traditional systemic therapies include short-term corticosteroids, cyclosporine (considered to be the gold standard), methotrexate, azathioprine, mycophenolate mofetil, and most recently leflunamide. Biologic therapies include recombinant monoclonal antibodies acting on the immunoglobulin E / interleukin-5 pathway (omalizumab, mepolizumab), acting as tumor necrosis factor-α inhibitors (infliximab, etanercept, adalimumab), and acting as T-cell (alefacept) and B-cell (rituxumab) inhibitors, as well as interferon γ and intravenous immunoglobulin. Efficacy, safety, and tolerability are reviewed for each medication.

Calcineurin inhibitors for the treatment of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic disease characterized by periods of remission and relapse. Therapeutic objectives for AD should be to quickly reduce disease symptoms by targeting pathophysiological pathways, and to provide long-term management by reducing recurrences.

OBJECTIVE

Calcineurin inhibitors currently appear to be one of the most promising alternative systemic and topical compounds to treat AD. This review focuses on new developments of topical calcineurin inhibitors, therapeutic regimens including long-term management, and prophylaxis of AD.

METHODS

The published clinical studies that present data on treatment of AD with calcineurin inhibitors were assessed.

RESULTS/CONCLUSION

Topical calcineurin inhibitors such as tacrolimus and pimecrolimus provide an effective treatment for AD. They are useful for long-term management and prophylaxis of AD. Safety concerns with regard to increased risk for lymphomas or skin cancer could not be confirmed but will remain under careful observation.

Topical tacrolimus in combination with simulated solar radiation does not enhance photocarcinogenesis in hairless mice

Numerous studies have demonstrated the utility of topical tacrolimus ointment in atopic dermatitis. However, there is a concern that local immunosuppression by calcineurin inhibitors may enhance dermal photocarcinogenesis and carcinogenesis. Therefore, we investigated the influence of topical tacrolimus ointment on squamous cell carcinoma formation in hairless female C3.Cg/TifBomTac immunocompetent mice exposed to solar simulated radiation (SSR). In a first experiment, mice (n = 200) had tacrolimus applied on their dorsal skin three times weekly followed by SSR (2, 4 or 6 standard erythema doses, SED) 3-4 h later. Tacrolimus did not reduce the time to tumor development and in the group receiving 4 SED it even had a protective effect (156 days vs 170 days, P = 0.008). In a second experiment, mice (n = 50) were irradiated with 6 SED three times weekly for 3 months and subsequently treated five times weekly with topical tacrolimus to mimic the use of tacrolimus on sun-damaged skin. The median time to the first skin tumor was 234 days in SSR + tacrolimus group compared with 227 days in the only SSR-irradiated group (P = 0.160). In a third experiment, mice (n = 25) had tacrolimus applied on their dorsal skin every day for 1 month, thereafter the group was irradiated with 4 SED three times weekly. The median time to the first skin tumor was 142 days in tacrolimus + SSR group compared with 156 days in the only SSR-irradiated group from experiment 1 (P = 0.363). We conclude that tacrolimus ointment does not accelerate photocarcinogenesis or induce any dermal carcinogenicity in hairless mice.

Tacrolimus in dermatology-pharmacokinetics, mechanism of action, drug interactions, dosages, and side effects: part I

The advent of tacrolimus at the end of the preceding century in the armamentarium of atopic dermatitis management was hailed as a breakthrough advance. It was, therefore, thought worthwhile to precisely review its origin and mechanism of action. Its topical application in the form of 0.03% to 0.1% ointments is rapidly effective and safe in pediatric and adult patients. Its use in atopic dermatitis ever since has been approved in Japan, the United States, Europe, and the Indian subcontinent. Thus, its local immunosuppressive action was fairly intriguing. Accordingly, its indications/uses were extended to cover several inflammatory dermatoses. Vitiligo, psoriasis, alopecia areata, contact hypersensitivity, lichen planus, pyoderma gangrenosum, ichthyosis linearis circumflexa, and skin grafting/transplant are a few unapproved indications and uses, in addition to miscellaneous dermatoses. At present, its therapeutic efficacy other then atopic dermatitis is confined to case studies, and large studies are warranted. At this point in time, therefore, it is conceivable that tacrolimus use should be carefully evaluated and used only when the conventional treatment has failed to yield favorable results. It deserves sizable caution for use in various dermatologic conditions pending its long-term safety and efficacy data in large patient populations.

Multiple lesions of cutaneous focal mucinosis in a teenager

A 19-year-old Hispanic woman presented to our clinic with a chief complaint of multiple pink papules on her face (Figure 1). The lesions were asymptomatic, had appeared several years before her consultation, and had remained stable in size. Similar lesions on her trunk and extremities had spontaneously resolved before presentation. She had no significant medical history and was not on any medications. Cutaneous examination was remarkable for a few scattered, well-demarcated, slightly raised pink papules and plaques with no scale, ranging from 0.5 to 1 cm in diameter. The lesions were distributed on the right cheek, right temple, left lower eyelid, and neck area. The rest of the cutaneous examination was unremarkable. A punch biopsy was performed from a lesion near the left premandibular area. Hematoxylin and eosin staining of the biopsy specimen revealed superficial perivascular dermatitis with a slight increase in the number of fibroblasts (Figure 2). Colloidal iron staining was diffusely positive with replacement of collagen with mucinous material in the dermal layer (Figure 3). Laboratory values for a complete blood cell count, metabolic panel, serum protein electrophoresis, urine protein electrophoresis, thyroid-stimulating hormone, and antinuclear antibody were within normal limits. The patient was diagnosed with cutaneous focal mucinosis. Because of cosmetic concerns, the patient declined surgical excision and intralesional corticosteroid injections. A 4-month trial of topical tacrolimus 0.1% ointment was ineffective.

The safety of tacrolimus ointment for the treatment of atopic dermatitis: a review

Tacrolimus ointment is a topical calcineurin inhibitor (TCI) that was developed specifically for the treatment of atopic dermatitis (AD). It is one of the most extensively tested dermatological products, with more than 19 000 patients (including approximately 7600 children) having participated in the tacrolimus ointment clinical development programme. Recent regulatory reviews have focused on the potential risk of malignancy with TCIs, based on their mode of action and the effects of systemic tacrolimus when given to transplant recipients. Studies have shown, however, that the systemic absorption of tacrolimus when applied topically is very low, with blood concentrations being below the level of quantification in most patients. Moreover, TCIs are not associated with a decrease in immunocompetence in the skin and there is no increase in the incidence of infections with long-term treatment. More than 5.4 million prescriptions for tacrolimus ointment have been issued worldwide, with no evidence of an increased risk of malignancy in adults or children compared with the general population. Similarly, epidemiological studies have failed to demonstrate an increased incidence of skin cancer in patients using TCIs. The most common adverse events (AEs) that occur with tacrolimus ointment treatment are transient application-site reactions, such as burning or pruritus. These complications are related to disease severity, and decrease in frequency over time as AD improves. The incidence of nonapplication-site AEs does not increase with long-term treatment, and most such events occurring in clinical trials were considered to be unrelated to therapy. Although it is important that clinicians are aware of the recent changes in product labelling, extensive clinical trials continue to show that tacrolimus ointment is well tolerated, and is generally an effective therapy for suitable patients with AD.

Contact Dermatitis

Contact dermatitis is a common skin disease caused by contact with irritants or allergens. Irritant contact dermatitis is a result of nonspecific irritant factors, which cause activation of mainly innate immunity, resulting in skin inflammation. Contact hypersensitivity, which manifests itself as allergic contact dermatitis, is result of adaptive immune response, where sensitization to hapten-carrier complexes leads to T-cell-mediated contact allergy. Subsequent contact with the hapten results in skin inflammation. This review concentrates on the role of cutaneous receptors in contact dermatitis and highlights potential targets for treatment interventions.

Comparative Effect of Tacrolimus and Betamethasone Valerate on the Passive Sustainable Hydration of the Stratum Corneum in Atopic Dermatitis

BACKGROUND

There is ample evidence that the skin barrier function is altered in atopic dermatitis. Little information is available about the effect of topical corticosteroids and calcineurin inhibitors on this function.

PURPOSE

To assess the water content and its rate of accumulation in the stratum corneum of atopic patients using an indirect electrometric method while on tacrolimus or betamethasone valerate treatment.

METHOD

Twenty-one patients with moderate atopic dermatitis affecting both forearms completed this double-blind randomized study. One forearm was treated twice daily for 3 weeks with 0.1% tacrolimus ointment. The other forearm was similarly treated with 0.12% betamethasone valerate ointment. Electrometric measurements were made under continuous occlusion secured by a Nova Dermal Phase Meter sensor probe. Assessments were performed at inclusion, after the 3-week treatment and after a further 3-week follow-up out of treatment.

RESULTS

During treatment, both compounds yielded a similar improvement in skin barrier function. Indeed, under probe occlusion, the rate of water accumulation was significantly decreased. This improvement was sustained after stopping the tacrolimus treatment. By contrast, the benefit was in part lost at the site that had been treated by betamethasone valerate.

CONCLUSION

The difference in the effect of the 2 compounds may be due to the negative influence of betamethasone valerate on the epidermal metabolism leading to progressive atrophy of the tissue. The better preservation of the skin barrier function after stopping tacrolimus treatment may help retarding relapses of atopic dermatitis.

In Vitro Diffusion of the Immunosuppressant Tacrolimus Through Human and Rabbit Corneas

PURPOSE

The aim of this study was to investigate the in vitro diffusion kinetics of tacrolimus (TAC) through rabbit and human corneas, and to evaluate the suitability of rabbit cornea as an in vitro permeability model for human cornea.

METHODS

A flow-through diffusion apparatus was used for all permeability experiments. The percentage of total (3)H-TAC diffusing across the corneas was determined over 24 h and fractions collected twice-hourly (20 degrees C; 1.5 mL/h). An F test was used for whole-curve comparisons, with a significance level of 5%.

RESULTS

Steady-state values for TAC across both types of corneas were not reached. Although the percentage of TAC diffusing across rabbit cornea was higher than that found for human cornea up to 18 h, there were no statistically significant differences. The percentages of total TAC diffusing across human and rabbit cornea at the 24-h time points were 0.38% +/- 0.02% and 0.36% +/- 0.01%, respectively.

CONCLUSIONS

Percentages of total TAC at the 24-h time points were approximately 4.9x and 4.1x higher than those found previously for cyclosporin A across human and rabbit corneas, respectively. Rabbit corneas are a suitable model for human corneas in in vitro permeability studies.

Discovery of Topical Calcineurin Inhibitors and Pharmacological Profile of Pimecrolimus

Using a newly developed model of allergic contact dermatitis in pigs, calcineurin inhibitors of the tacrolimus and ascomycin type were shown to have a highly anti-inflammatory action after topical application. These findings provided the first pharmacological evidence of the efficacy of this novel class of topical agents in the treatment of inflammatory skin diseases, and, thus, their potential to become the first alternative to corticosteroids in more than 40 years. As a result of a large research program into ascomycins, pimecrolimus (Elidel(R), SDZ ASM 981) was selected for development due to its favorable pharmacology and safety profile, alongside tacrolimus (Protopic(R), FK 506). In vitro, pimecrolimus inhibits the transcription and release of pro-inflammatory cytokines in T cells. Similar to the corticosteroids, betamethasone-17-valerate and dexamethasone, pimecrolimus is effective at nanomolar concentrations. Targeting mainly T cells, pimecrolimus has, however, a more specific mode of action. Moreover, in contrast to corticosteroids, pimecrolimus has no effect on Langerhans' cells, the professional antigen- presenting dendritic cells of the skin that are crucial for local immunosurveillance. When applied topically, pimecrolimus exerts a high and selective anti-inflammatory activity in the skin, shows minimal percutaneous absorption, and has a low potential to affect systemic immunoreactions. Pimecrolimus cream 1% has proven to be well tolerated, safe, and highly effective in clinical studies in patients with atopic dermatitis.

Simultaneous determination of three isomeric metabolites of tacrolimus (FK506) in human whole blood and plasma using high performance liquid chromatography–tandem mass spectrometry

An ammonium-adduct based liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous determination of three isomeric metabolites of tacrolimus (FK506), 13-O-demethylated (M1), 31-O-demethylated (M2) and 15-O-demethylated (M3) tacrolimus in human whole blood and plasma. These metabolites and the internal standards were extracted from biological matrix by methylbutyl ether (MTBE). Separation was achieved on a Genesis C(18) column with a gradient mobile phase elution. Ammonium-adduct ions formed by a Turbo Ionspray in positive ion mode were used to detect each analyte and internal standard. The MS/MS detection was by monitoring the fragmentation of 807.5-->772.4 (m/z) for M1, 807.5-->754.5 (m/z) for both M2 and M3, 795.5-->760.5 (m/z) for IS1 (FR298701) and 961.5-->908.5 (m/z) for IS2 (FR290198) on a triple quadrupole mass spectrometer (Sciex API 3000). The retention times were approximately 4.1 min for M1, 6.8 min for M2, 6.0 min for M3, and 3.9 min for IS1 and 6.4 min for IS2, respectively. The validated dynamic range was 0.2-20 ng/ml for all three metabolites based on a sample volume of 0.25-ml. The linearity of calibration curves for M1, M2, and M3 in both matrices had a correlation coefficient of >/=0.9984. In whole blood, validation data showed intra-batch (n=6) CVs of </=5.9% and REs between -4.9 and 3.6% and inter-batch (N=18) CVs of </=4.9% and REs between -3.5 and 1.5% for all three metabolites. In human plasma, validation data showed intra-batch (n=6) CVs of </=7.3% and REs between -5.1 and 7.6% and inter-batch (N=18) CVs of </=6.6% and REs between -0.3 and 4.7% for all three metabolites. Extraction recoveries were 72% for M1, 87% for M2, 69% for M3, 79% for IS1, and 74% for IS2 from blood; and 94% for M1, 96% for M2, 98% for M3, 92% for IS1, and 93% for IS2 from plasma. All three metabolites in human blood and plasma were stable for three freeze-thaw cycles, or 24-h ambient storage, or 12 months storage at approximately -80 degrees C. Extracted samples were stable for at least 50h at room temperature (RT). This method has been successfully used to analyze whole blood and plasma samples from human pharmacokinetic studies. Several key factors affecting the performance of the assay methods have also been addressed briefly.