Experimental chemotherapy-induced skin necrosis in swine. Mechanistic studies of anthracycline antibiotic toxicity and protection with a radical dimer compound

Reactivity vs. selectivity of quinone methides: synthesis of pharmaceutically important molecules, toxicity and biological applications

Quinone methides (QMs) are considered to be highly reactive intermediates because of their aromatization both in chemical and biological systems. Being highly accessible, quinone methides (QMs) have been widely exploited and their concurrent use has been manifested for the synthesis of tertiary and quaternary carbon centers of bioactives, drugs and drug-like molecules. In this feature article, the synthetic routes, structure-reactivity relationships and synthetic applications of quinone methides are discussed. Formation of the intermediates during bioactivation of different chemical entities and possible chemical manifestations leading to their toxicity in biological systems are also covered.

Anthracycline Extravasation: A Comprehensive Review of Experimental and Clinical Treatments

An accidental extravasation of anthracycline-containing chemotherapy is a feared complication that may lead to necrosis and severe tissue destruction. For four decades, much effort has been done to prevent and treat this devastating condition. Savene™ has recently been proved to be very effective, and is the only approved treatment against anthracyline extravasation. It is thus now widely recommended. The present article represents a comprehensive review of, and historical insight to, the experimental and clinical studies of surgical and non-surgical treatments of extravasation during forty years of clinical anthracycline treatment.

A murine experimental anthracycline extravasation model: pathology and study of the involvement of topoisomerase II alpha and iron in the mechanism of tissue damage

The bisdioxopiperazine topoisomerase II catalytic inhibitor dexrazoxane has successfully been introduced into the clinic as an antidote to accidental anthracycline extravasation based on our preclinical mouse studies. The histology of this mouse extravasation model was investigated and found to be similar to findings in humans: massive necrosis in the subcutis, dermis and epidermis followed by sequestration and healing with granulation tissue, and a graft-versus-host-like reaction with hyperkeratotic and acanthotic keratinocytes, occasional apoptoses, epidermal invasion by lymphocytes and healing with dense dermal connective tissue. The extension of this fibrosis was quantified, and dexrazoxane intervention resulted in a statistically significant decrease in fibrosis extension, as also observed in the clinic. Several mechanisms have been proposed in anthracycline extravasation cytotoxicity, and we tested two major hypotheses: (1) interaction with topoisomerase II alpha and (2) the formation of tissue damaging reactive oxygen species following redox cycling of an anthracycline Fe(2+) complex. Dexrazoxane could minimise skin damage via both mechanisms, as it stops the catalytic activity of topoisomerase II alpha and thereby prevents access of anthracycline to the enzyme and thus cytotoxicity, and also acts as a strong iron chelator following opening of its two bisdioxopiperazine rings. Using the model of extravasation in a dexrazoxane-resistant transgenic mouse with a heterozygous mutation in the topoisomerase II alpha gene (Top2a(Y165S/+)), we found that dexrazoxane provided a protection against anthracycline-induced skin wounds that was indistinguishable from that found in wildtype mice. Thus, interaction with topoisomerase II alpha is not central in the pathogenesis of anthracycline-induced skin damage. In contrast to dexrazoxane, the iron-chelating bisdioxopiperazine ICRF-161 do not inhibit the catalytic cycle of topoisomerase II alpha. This compound was used to isolate and test the importance of iron in the wound pathogenesis. ICRF-161 was found ineffective in the treatment of anthracycline-induced skin damage, suggesting that iron does not play a dominant role in the genesis of wounds.

Evaluation and treatment of chemotherapy extravasation injuries

Extravasation of chemotherapeutic vesicant agents can result in significant tissue damage, alteration in limb function, and pain. Quality of life for long-term survivors can be severely impacted by negative sequelae from vesicant extravasation. Currently, there is no known preventive therapy. Early detection and intervention are paramount to halt tissue damage and reduce the chance of permanent disability or disfigurement. This article provides an overview of known chemotherapeutic vesicants (mechlorethamine, mitomycin-C, doxorubicin, daunomycin, vincristine and vinblastine), associated theories of tissue destruction, assessment techniques for peripheral intravenous sites, vascular access devices and central venous lines, current treatment strategies, and investigational therapies. A brief discussion of the legal implications of extravasation injuries and recommended key points for medical record documentation are included.

Use of subatmospheric pressure to prevent doxorubicin extravasation ulcers in a swine model

Application of subatmospheric pressure to sites injected with doxorubicin prevented ulcer formation in treated sites (0 ulcers/16 sites) compared to control wounds (10 ulcers/16 sites) in a pig model.

BACKGROUND AND OBJECTIVES

Extravasation of doxorubicin hydrochloride (Adriamycin) frequently causes chronic ulcers, which usually progress and expose underlying structures such as tendons and bone. The exact mechanism of action that causes cell death and the chronic ulcers is unknown.

METHODS

Eight sites were injected intradermally with doxorubicin on each of 4 pigs. Four sites on each animal served as untreated controls. The remaining four sites were exposed to 125 mm Hg subatmospheric pressure applied 1 h after injection. The sites were observed on a three times per week schedule. Sites that did not develop ulcers were re-injected up to a total of four injections. The animals were observed for 5 weeks.

RESULTS

Ten of sixteen control sites developed ulcers. No subatmospheric pressure treated sites developed ulcers. The incidence of ulcer formation was significantly less for treated wounds compared to control wounds at P < 0.001 by Fisher's exact test.

CONCLUSIONS

This physical modality appears to successfully prevent ulcer formation after doxorubicin injection.

Prevention of adriamycin-induced skin necrosis with various free radical scavengers

Infiltration of antitumor agents into subcutaneous tissues may either result in a local area of self-resolving inflammation or progress to full-thickness loss of skin and underlying vital structures. Inadvertent extravasation of adriamycin can result in severe tissue necrosis. The mechanism of this tissue damage is believed to be release of oxygen free radicals into the tissue. After adriamycin extravasation, the treatment groups were made up according to drugs used, EGb 761, pentoxifylline, alpha-tocopherol acetate, and alpha-tocopherol succinate in rats. To prevent the necrosis and to decrease the tissue malondialdehyde levels, the most effective agent was found to be EGb 761, and pentoxifylline was also effective (P < 0.001). No difference was found between topical lanoline and saline (P > 0.05). The maximum ulcer diameter was obtained in 2 weeks. The maximum tissue malondialdehyde levels were obtained in 24 h, and in comparison to the control group the treatment groups showed lower levels. Our aim is to show the role of free radicals in the formation of skin necrosis as a cause of adriamycin extravasation and to prevent or decrease the skin necrosis using various free radical scavengers.

Protective effect of doxorubicin in vitamin C or dimethyl sulfoxide against skin ulceration in the pig

BACKGROUND

Accidental extravasation of doxorubicin leads to skin necrosis and significant morbidity. Based on our previous work in the rat, we hypothesized that the free radical scavengers dimethyl sulfoxide (DMSO) and vitamin C prevent doxorubicin-induced skin ulcers in white swine.

METHODS

Fifteen white swine were anesthetized and injected with 0.5 mg of doxorubicin (1 mg/ml) intradermally delivered in saline, 10% DMSO, 20% DMSO, vitamin C (1 mg/ml), or vitamin C in 20% DMSO. Presence of skin ulceration and ulcer size, in the two greatest dimensions, was determined weekly for 3 weeks.

RESULTS

Delivery of doxorubicin in DMSO and/or vitamin C lowered the ulcer incidence from 87% to 27% (p < 0.0001) when compared with delivery in saline.

CONCLUSION

We conclude that the free radical scavengers DMSO and vitamin C are capable of lowering the incidence of doxorubicin-induced skin ulcers and could significantly lessen the morbidity associated with doxorubicin extravasation.

Time-related increases in cardiac concentrations of doxorubicinol could interact with doxorubicin to depress myocardial contractile function

1. The present study evaluated the time-dependency of acute anthracycline cardiotoxicity by varying the duration of exposure of rabbit isolated atria to doxorubicin and determining changes (1) in contraction and relaxation and (2) in atrial concentrations of doxorubicin and its C-13 hydroxy metabolite, doxorubicinol. 2. Following addition of doxorubicin (175 microM) to atria, contractility (dF/dt), muscle stiffness (resting force, RF) and relaxation (90% relaxation time, 90% RT) were monitored for a 3.5 h period. 3. Doxorubicin (175 microM) progressively diminished mechanical function (decreased dF/dt, increased RF and prolonged 90% RT) over 3 h. Doxorubicinol (1.8 microM), however, failed to produce time-related cardiac dysfunction; it depressed contractile function and increased muscle stiffness during the first 30 min without causing additional cardiac dysfunction during the remaining 3 h of observation. Doxorubicinol had no effect on 90% RT. 4. During treatment with doxorubicin, atria contained considerably more doxorubicin than doxorubicinol (ratio of doxorubicin to doxorubicinol ranged from 778 to 74 at 0.5 and 3 h, respectively). Elevations of doxorubicin and doxorubicinol in atria paralleled the degree of dysfunction of both contraction and relaxation; increases in muscle stiffness, however, were more closely associated with increases of doxorubicinol than doxorubicin. 5. To probe the relation between cardiac doxorubicinol and myocardial dysfunction further, without confounding effects of cardiac doxorubicin, concentration-response experiments with doxorubicinol (0.9-7.2 microM) were conducted. 6. Plots of doxorubicinol concentrations in atria vs contractility indicated that the cardiac concentration of doxorubicinol, at which contractility is reduced by 50%, is five fold lower in doxorubicin-treated than in doxorubicinol-treated preparations. Thus, doxorubicin and doxorubicinol appear to interact to depress contractile function.7. Cardiac concentrations of both doxorubicin and doxorubicinol, as observed in these studies, were found to stimulate markedly Ca2+ release from isolated SR vesicles, but 3 microM doxorubicinol promoted a 15 fold greater release rate than 3 microM doxorubicin.8. Our observations coupled with the previously reported finding that doxorubicinol inhibits Ca2+loading of SR, suggests that doxorubicinol accumulation in heart contributes to the time-dependent component of doxorubicin cardiotoxicity, through a mechanism that could involve perturbations of Ca2+ homeostasis.

Biological and toxicological consequences of quinone methide formation

Quinone methides are a class of reactive, electrophilic compounds which are capable of alkylating cellular macromolecules. They are formed during xenobiotic biotransformation reactions and are hypothesized to mediate the toxicity of a large number of quinone antitumor drugs as well as several alkylphenols. In addition, oxidation of specific endogenous alkylphenols (e.g. coniferyl alcohol) and alkylcatechols (e.g. N-acetyldopamine, dopa) to quinone methides plays an important role in the synthesis of several complex plant and animal polymers, including lignin, cuticle and melanin. The role of quinone methides in these various processes is reviewed.

DMSO protects against adriamycin-induced tissue necrosis

Inadvertent extravasation of Adriamycin (Adria) can result in severe tissue necrosis. The mechanism of this tissue damage is believed to be the release of free radicals into the tissue. Topical applications of dimethylsulfoxide (DMSO) used after Adria extravasation have been shown to decrease ulcer size. This may be due to DMSO's ability to scavenge free radicals. However, effective topical therapy requires prompt recognition of extravasation, which is often difficult. We hypothesized that the delivery of Adria in low concentrations DMSO would reduce Adria-induced ulcer size and ulcer incidence caused by Adria extravasation. To test this hypothesis, 180, male Sprague-Dawley rats were randomly allocated into three treatment groups of 60 each. All three groups received intradermal injections of Adria (1 mg) diluted in 0.5 cc of saline (Group 1), 10% DMSO (Group 2), or 20% DMSO (Group 3). Rats were observed for 4 weeks. Ulcer incidence (%) and size of ulcers (mm2) were assessed over time. Area of skin ulceration was calculated as the product of the two greatest diameters. Statistical evaluation of the differences in incidence and ulcer size between Group 1 and Groups 2 or 3 were evaluated using analysis of variance. Delivery of Adriamycin in 10 or 20% DMSO resulted in a statistically significant (P less than 0.001) decrease in the incidence of ulceration caused by intentional Adria extravasation.

Mitoxantrone. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in the chemotherapy of cancer

Mitoxantrone is a dihydroxyanthracenedione derivative which as intravenous mono- and combination therapy has demonstrated therapeutic efficacy similar to that of standard induction and salvage treatment regimens in advanced breast cancer, non-Hodgkin's lymphoma, acute nonlymphoblastic leukaemia and chronic myelogenous leukaemia in blast crisis; it appears to be an effective alternative to the anthracycline component of standard treatment regimens in these indications. Mitoxantrone is also effective as a component of predominantly palliative treatment regimens for hepatic and advanced ovarian carcinoma. Limited studies suggest useful therapeutic activity in multiple myeloma and acute lymphoblastic leukaemia. Regional therapy of malignant effusions, hepatic and ovarian carcinomas has also been very effective, with a reduction in systemic adverse effects. Mitoxantrone inhibits DNA synthesis by intercalating DNA, inducing DNA strand breaks, and causing DNA aggregation and compaction, and delays cell cycle progression, particularly in late S phase. In vitro antitumour activity is concentration- and exposure time-proportional, and synergy with other antineoplastic drugs has been demonstrated in murine tumour models. Leucopenia may be dose-limiting in patients with solid tumours, whereas stomatitis may be dose-limiting in patients with leukaemia. Other adverse effects are usually of mild or moderate severity although cardiac effects, particularly congestive heart failure, may be of concern, especially in patients with a history of anthracycline therapy, mediastinal irradiation or cardiovascular disease. Mitoxantrone displays an improved tolerability profile compared with doxorubicin and other anthracyclines, although myelosuppression may occur more frequently. Thus, mitoxantrone is an effective and better tolerated alternative to the anthracyclines in most haematological malignancies, in breast cancer and in advanced hepatic or ovarian carcinoma. Further studies may consolidate its role in the treatment of these and other malignancies.