Treatment of aquagenic pruritus with topical capsaicin cream

BACKGROUND

Aquagenic pruritus is characterized by pruritus after contact with water; there are no objective cutaneous changes. Capsaicin, which induces the release of neuropeptides from A delta and C cutaneous nerve fibers, has been successfully used in the treatment of several dermatoses associated with pruritus. Among the many different neuropeptides present in human skin, the undecapeptide substance P has been shown to cause pruritus.

OBJECTIVE

We evaluated the clinical effect and searched for alterations in cutaneous neuropeptidergic fibers before and after treatment with capsaicin cream.

METHODS

Five patients with aquagenic pruritus were treated with capsaicin cream 0.025%, 0.5% or 1.0% three times daily for 4 weeks. Direct immunofluorescence (DIF) was performed before and after treatment to evaluate the storage of neuropeptides in the A delta and C type cutaneous nerve fibers.

RESULTS

Before treatment (when by DIF the neuropeptidergic fibers appeared filled with neuropeptides), contact with water consistently provoked itching. After capsaicin treatment (when by DIF the neuropeptidergic fibers were depleted of neuropeptides), contact with water did not evoke pruritus. Areas of skin treated with the vehicle alone showed no clinical improvement or change in neuropeptide content.

CONCLUSION

This study suggests that neuropeptides, including substance P, may contribute to mediating the itch in aquagenic pruritus.

Mesoglycan treatment restores defective fibrinolytic potential in cutaneous necrotizing venulitis

BACKGROUND

Cutaneous necrotizing venulitis (CNV) is a clinical disorder associated with segmental inflammation and fibrinoid necrosis of the dermal venules. It usually presents clinically as palpable purpura, even sometimes as nodules, bullae, ulcers, and urticarial lesions. This form, when showing as leukocytoclastic vasculitis is apparently characterized by the tissue deposition of circulating immune complexes and by reduced cutaneous (CFA) and plasma (PFA) fibrinolytic activity due to reduced release of plasminogen activator (PA) from the venular endotheliocytes. Reduced CFA and PFA cause large amounts of fibrin deposits in both intra- and perivascular areas, which are able to magnify and self perpetuate the inflammatory processes following immune complex deposition.

METHODS

We have studied both the PFA and CFA potential (the maximum amount of PA released in the skin after certain stimuli) and the deposits of immunoglobulins, C3, and fibrin related antigen, before and after intradermal injection of histamine (a substance able to provoke endothelial release of PA), in three subjects affected by CNV before and 20 days after 10 mg/kg/day I.M. treatment with the fibrinolytic agent mesoglycan.

RESULTS

Cutaneous fibrinolytic activity and CFA potential, reduced prior to treatment, was normal after treatment, while the deposits of immunoglobulins (IgA, IgG and IgM), C3, and fibrin related antigen, detected with direct immune fluorescence (DIF) showed similar findings before and after treatment.

CONCLUSIONS

These data suggest that reduced CFA may play a major role in the pathogenesis of the immunologically mediated injury in CNV. The intraperivascular deposition of fibrin is favored. The fibrinolytic agent mesoglycan seems effective in restoring defective fibrinolysis in patients affected by cutaneous necrotizing venulitis, suggesting that in cases with reduced cutaneous fibrinolytic activity (or potential) the use of a fibrinolytic agent should be considered.

Substance P provokes cutaneous erythema and edema through a histamine-independent pathway

Substance P is a neuropeptide (contained in/and released from the A delta and C nerve fibers of the skin), which provokes erythema, edema, and pruritus after intradermal injection. Local pretreatment with capsaicin produces decreased substance P-dependent erythema, with edema similar to that observed before pretreatment with capsaicin. We injected histamine and in a parallel experiment, substance P in five volunteers before and after local treatment with capsaicin, with 48/80, after 5 days of hydroxyzine. The injection of SP provoked erythema centered by a wheal. After treatment with 48/80, SP provoked increased erythema and a wheal. After hydroxyzine treatment, the injection of histamine produced no erythema or edema in four of the five subjects, while SP provoked erythema in all five subjects and edema similar to that observed before treatment with hydroxyzine. These data support the hypothesis that substance P provokes erythema and edema both with histamine-dependent and histamine-independent pathways.

[Pityriasis rosea-like skin eruptions caused by captopril]

Captopril is an antihypertensive drug that works by inhibiting the angiotensin-converting enzyme and provokes increased levels of plasma quinine. In the case here reported a picture of pityriasis rosea-like reaction is described. The frequency of the observed and reported reactions by captopril suggests a particular caution in the use of this drug.

[Preliminary experiences with chemotactic activity of CGRP using the skin window test]

The neuropeptide CGRP (Calcitonin Gene-Related Peptide) develops in sensory fibers of the human skin a series of well proven biological effects and seems particularly correlated with the neurogenic inflammation. In the site of intradermic injection of 50 pmol of CGRP, neutrophilic inflammation was documented. For this reason we have studied using the skin window test the chemotactic actions of this neuropeptide in vivo. The apposition of CGRP (12.5 pmol) on the abraded skin modifies neutrophilic egress, increasing that effect in a significant way in comparison with controls. The action on neutrophils of CGRP helps to explain the importance of this neuropeptide in the genesis of the "Neurogenic inflammation".

[Defocused CO2 laser in the treatment of leg ulcers. Preliminary results]

We studied the therapeutic action of CO2 Laser on leg ulcers due to chronic venous hypertension in 30 subjects. Our findings show good results in reducing pain and leg oedema and wound healing.