Toxicology of oncologic drugs

Toxicity, outcome, and management of anthracycline overdoses in 16 dogs

Background

Despite multiple reports of chemotherapy overdoses (ODs) in human and veterinary medicine, anthracycline ODs have been described infrequently.

Hypothesis/Objectives

Describe toxicities, treatments, and overall outcome after anthracycline OD in dogs.

Animals

Twelve mitoxantrone (MTX) and 4 doxorubicin (DOX) ODs were evaluated.

Methods

Multicenter retrospective analysis. The American College of Veterinary Internal Medicine oncology and internal medicine listservs were solicited for cases in which a chemotherapy OD occurred.

Results

Sixteen anthracycline cases were collected. Anthracycline ODs occurred because of an error in chemotherapy preparation (n = 9), or dose miscalculation (n = 7). The overall median OD was 1.9× (range, 1.4‐10×) the prescribed amount. Most ODs were identified immediately after drug administration (n = 11), and the majority of patients were hospitalized on supportive care (n = 11) for an average of 8 days (range, 3‐34 days). Adverse events after the OD included neutropenia (94%), thrombocytopenia (88%), anemia (63%), diarrhea (63%), anorexia (56%), vomiting (38%), lethargy (31%), and nausea (25%). Two patients did not survive the OD. High grade neutropenia was common and did not appear to be mitigated by the administration of filgrastim.

Conclusions and Clinical Importance

All patients received supportive care after identifying the OD and death was uncommon. Further evaluation is needed to determine ideal therapeutic guidelines anthracycline OD.

Pathophysiological Mechanisms of Gastrointestinal Toxicity

Humans swallow a great variety and often large amounts of chemicals as nutrients, incidental food additives and contaminants, drugs, and inhaled particles and chemicals, thus exposing the gastrointestinal tract to many potentially toxic substances. It serves as a barrier in many cases to protect other components of the body from such substances and infections. Fortunately, the gastrointestinal tract is remarkably robust and generally is able to withstand multiple daily assaults by the chemicals to which it is exposed. Some chemicals, however, can affect one or more aspects of the gastrointestinal tract to produce abnormal events that reflect toxicity. It is the purpose of this chapter to evaluate the mechanisms by which toxic chemicals produce their deleterious effects and to determine the consequences of the toxicity on integrity of gastrointestinal structure and function. Probably because of the intrinsic ability of the gastrointestinal tract to resist toxic chemicals, there is a paucity of data regarding gastrointestinal toxicology. It is therefore necessary in many cases to extrapolate toxic mechanisms from infectious processes, inflammatory conditions, ischemia, and other insults in addition to more conventional chemical sources of toxicity.

Associação do methimazole e do ondansetron à quimioterapia com cisplatina em cães submetidos a quatro diferentes protocolos de fluidoterapia

Utilizaram-se 12 cães, machos, distribuídos em quatro grupos (G) experimentais, selecionados de acordo com o tempo de fluidoterapia com solução fisiológica 0,9%: G1 (sem fluidoterapia), G2 (uma hora de fluidoterapia antes da cisplatina), G3 (uma hora de fluidoterapia antes da cisplatina e uma hora após) e G4 (duas horas de fluidoterapia antes da cisplatina e uma após). Todos os animais receberam a cisplatina (70mg/m²), pela via intravenosa, sendo os ciclos de quimioterapia realizados em intervalos de três semanas, num total de três ciclos. O ondansetron (0,4mg/kg) foi administrado pela via intravenosa, a cada oito horas, no dia da quimioterapia e, a seguir, a cada 12 horas, por dois dias. O methimazole (40mg/kg) foi pela via oral, 30 minutos antes da cisplatina e quatro horas após. Avaliaram-se os parâmetros hematológicos, bioquímicos, urinários e dosagem de tiroxina e triiodotironina a cada sete dias até o término do experimento. Esse protocolo foi eficaz e seguro em cães que permaneceram sob fluidoterapia durante duas a três horas. Os animais que não receberam fluidoterapia e os que ficaram somente uma hora sob infusão intravenosa de solução fisiológica apresentaram alterações que resultaram em não-recomendação do protocolo.

Multivariate Survival Analysis of Histological Parameters and Clinical Presentation in Canine Cutaneous Mast Cell Tumours

The Patnaik histological grade is a good method for the prediction of long-term mast cell tumour behaviour but it is influenced by subjective inter-observer variations and intratumoral heterogeneity. The present study evaluated each of the histopathological parameters used to formulate Patnaik's grade in terms of prognosis and tested whether they have a different prognostic sensitivity, thereby disclosing which could be considered more useful in the prediction of tumour recurrence and patient survival. Clinical presentation (single or multiple tumours) was also considered as possible prognostic factor. The results demonstrated that individual histological criteria together with multiple presentation may be of value in predicting the outcome of mast cell tumours. Among these, invasiveness (beta1.85; standard error 1.15) and the number of mitotic figures (beta3.01; standard error 1.18) showed high prognostic significance (Cox proportional hazard regression for censored data; chi-squared = 15.52, degree of freedom = 6, p = 0.016) and could serve as reliable prognostic indicators avoiding more subjective parameters such as cellular differentiation, nuclear morphology and tumoural pattern.

Avaliação da função renal de cães sob dois protocolos para administração da cisplatina

OBJETIVO: Avaliar a função renal de cães sadios, sob dois protocolos para administração de cisplatina. MÉTODOS: Todos os animais foram submetidos a três sessões de quimioterapia com cisplatina (60mg/m², iv) a intervalos de 21 dias. Foi realizada fluidoterapia com solução de cloreto de sódio a 0,9%, (25mL/kg/hora,iv), durante duas horas e, após administração de cisplatina, por mais uma hora. Os animais do grupo 2 receberam furosemida (2mg/kg, iv) 20 minutos antes da administração da cisplatina. A avaliação da função renal foi feita por exame clinico, urinálise, concentrações séricas de uréia e creatinina, clearance de creatinina, excreção fracionada de sódio e de potássio e razão proteína: creatinina urinária. As avaliações foram feitas imediatamente antes e 1, 2, 5, e 21 dias após cada uma das três sessões de quimioterapia. RESULTADOS: Mantiveram-se dentro da normalidade, não sendo detectados sinais de lesões ou insuficiência renal. Os animais que não receberam furosemida sofreram aumento gradativo nas concentrações séricas de creatinina e diminuição no clearance da mesma. CONCLUSÃO: O regime de fluidoterapia empregado mostra ser efetivo em minimizar a ação nefrotóxica da cisplatina e benefício adicional importante é obtido pela administração de furosemida.

Toxic and metabolic causes of seizures

Seizures are a relatively nonspecific response of the cerebral cortex to insult and can be caused by a variety of toxic or metabolic diseases. Seizure in response to extracranial disease are called reactive seizures. Toxins cause seizures by altering the balance of excitation and inhibition in the nervous system or interfering with energy metabolism. Many therapeutic or illicit drugs will cause seizures through similar mechanisms. Metabolic diseases can cause seizures by interfering with energy metabolism, changing osmolality, or producing endogenous toxins. In addition, metabolic disease may alter the pharmacokinetics of antiepileptic drugs or drugs that have the potential to cause seizures. While seizures represent a serious sign for many of these conditions, reactive epilepsy always carries the possibility that the seizures may be eliminated if the underlying cause is detected and corrected.

Therapy for feline dermatoses

This article compiles information on various therapies used in feline dermatology. Information on the following therapeutic agents and devices is discussed: antibiotics, antifungals, antileprosy drugs, antiparasiticides, antivirals, antihistamines, behavior modification drugs, fatty acids, progestogens, steroids, immunomodulating drugs, chemotherapeutic/immunosuppressive agents, retinoids, mechanical devices, hyposensitization, immunotherapy, food elimination trials, hypoallergenic diets, and miscellaneous topical agents such as polyhydroxydine solution, tar, and benzocaine-containing creams.