George R. Thompson

Bleomycin-induced interstitial pneumonia in dogs

The intravenous administration of Bleomycin to 10 dogs at different dosages resulted in varying degrees of interstitial pneumonia in all cases and a lower incidence of nephrosis, foot pad excoriation and ulceration, onychoptosis, and alopecia. Pulmonary changes did not occur as a simple dose-related phenomenon. The lesions required at least 38 days to become apparent and appeared to increase in severity with time. Even at the lowest dose used (0·625 mg/kg body weight) very severe changes were seen 128 days after cessation of therapy. Morphological features of interstitial pneumonia were subpleural localization, focal mesothelial hyperplasia, marked hyperplasia and metaplasia of type II pneumocytes, fetalization of alveoli, and a pleomorphic inflammatory infiltrate. In cross-sections of lung lobes selected for histology approximately 1 to 22% of the parenchyma contained lesions. Involved areas showed marked elastosis, excess of reticular fibres, fibrosis, and increased acid mucopolysaccharides. The administration of Bleomycin produced pulmonary changes similar in many respects to those reported in busulphan-treated patients and desquamative interstitial pneumonia. The finding of interstitial pneumonia and pulmonary fibrosis in dogs treated with low doses over prolonged periods points the need to monitor pulmonary function in humans treated with Bleomycin.

Chronic oral toxicity of cannabinoids in rats

Abstract The preclinical toxicity of Δ9-tetrahydrocannabinol (Δ9-THC), Δ8-THC and a crude marihuana extract (CME) was evaluated in Fischer rats. The compounds were dissolved in sesame oil and administered po for 119 consecutive days at doses of 50, 250, 400 or 500 mg/kg/day for Δ9- and Δ8-THC, or 150, 750, 1200 or 1500 mg/kg/day for CME. These high dose levels were 30–300 times the usual oral dose in man and were chosen specifically to induce toxicity in rats. A biphasic toxicity pattern was characterized by generalized depression to which tolerance developed during the first week. Thereafter, hyperactivity, irritability and aggressiveness progressed and convulsions occurred by day 50. Cumulative toxicity occurred during the first few days of depression as indicated by increased chronic vs acute mortality. The singledose LD1 and LD4 for Δ9-THC produced 23 and 70% mortality in male rats which were treated chronically. A consistently higher incidence of mortality occurred in females than in males, but essentially all deaths from all three compounds occurred during the interval 36 to 72 hr after initial treatment. Dose-related hypothermia and bradypnea were prevalent and coincided with the interval for mortality. Growth in all treated groups was persistently decreased in a dose-related manner (30–130%) despite an increased consumption of food and water after approximately day 50; abdominal fat stores were depleted for extended periods. Organ weights decreased for uterus, prostate, ovary and spleen, and increased for adrenals, but pathologic changes in these organs were limited to splenic hypocellularity and vacuolization of the adrenal. Hematologic and biochemical parameters were generally normal except for mild leukopenia, increased SGOT and decreased coagulation time. Toxicity was similar for the three compounds and suggested a prominent effect on endocrinologic systems.

Comparison of acute oral toxicity of cannabinoids in rats, dogs and monkeys

Abstract For preclinical toxicologic evaluation, Δ9-tetrahydrocannabinol (Δ9-THC), Δ8-THC, and Cannabis extract were administered po to rats, dogs and monkeys as solutions in either absolute ethanol, sesame oil, or sesame oil with 2.5–9.0% ethanol. All three compounds were significantly more potent in female than in male Wistar-Lewis and Fischer rats. However, within the dosage range of 225–3600 mg/kg, Δ9-THC and Δ8-THC produced the same lethality, while both isomers were approximately twice as potent as the Cannabis extract. Death due to all three compounds consistently occurred between 36 and 72 hr after treatment regardless of the dose level or sex of the rats. Mortality in rats apparently resulted from severe hypothermia and other central effects. Toxicity was characterized by severe hypothermia, bradypnea, rapid weight loss, inactivity, wide stance, ataxia, muscle tremors, and prostration. Rats treated with equimolar amounts of tetrahydrocannabinol from the three compounds exhibited equivalent diversities and severities of clinical signs. In dogs and monkeys, single oral doses of Δ9-THC and Δ8-THC between 3000 and 9000/mg/kg were nonlethal. Predominant toxic signs in dogs included drowsiness, ataxia, prostration, anesthesia, tremors, mild hypothermia, salivation, emesis, and anorexia. Toxic signs in monkeys included hyperreactivity to stimuli, lethargy, drowsiness, characteristic huddled posture, slow movements, abnormal eating procedures and sedation. Histopathologic alterations did not occur in either dogs or monkeys.

Oral and intravenous toxicity of Δ9-tetrahydrocannabinol in rhesus monkeys☆☆☆

The toxicity of Δ9-THC was evaluated in 35 rhesus monkeys treated acutely po or iv; in 28 monkeys treated po for 28 days with 0, 50, 250 or 500 mg/kg/day; or in 16 monkeys treated iv for 28 days with 0, 5, 15 or 45 mg/kg/day. The high subacute doses selected from acute toxicity studies were chosen to establish toxicity, not to simulate human dosages. No deaths occurred in monkeys treated acutely po with up to 9000 mg/kg, but all monkeys treated acutely iv with 128 mg/kg or more died from respiratory arrest and cardiac failure. In the subacute oral study 2 of 8 monkeys treated with 500 mg/kg/day became moribund on days 10 and 14, and 1 of 6 monkeys treated with 50 mg/kg/day became moribund on day 16. Primary pathologic changes in these 3 moribund monkeys included atrophy of the pancreas, hemorrhagic ulcerative colitis, myeloid hyperplasia of the bone marrow, vacuolar nephrosis and severe serum electrolyte imbalance. All other monkeys were normal at necropsy. In the subacute iv trials, 2 of 4 monkeys treated with 45 mg/kg/day died on days 8 and 19 as a result of acute hemorrhagic pneumonia, but injection site edema, necrosis, ulceration and fibrosis also occurred. Behavioral and physiologic changes were similar in both studies and included lethargy, huddled posture, bradypnea, hypothermia, bradycardia, weight loss, anorexia and constipation. Tolerance and cumulative toxicity were also similar for the 2 studies, but monkeys treated iv showed dose-related anemia and increased BSP retention while no blood changes occurred in monkeys treated po. Pathologic changes in deceased monkeys were associated with the route of administration.

Preclinical toxicologic evaluation of bleomycin (NSC 125 066), a new antitumor antibiotic

Abstract Bleomycin, a potent antitumor antibiotic obtained from Streptomyces verticillus , was administered to 14 dogs at doses from 0.312 to 5.0 mg/kg iv every 4 days for 6 to 28 wk. The resultant toxicity was atypical for most antitumor agents. Nondose-related interstitial pneumonia and pulmonary fibrosis restricted to pleural and subpleural areas were the treatment limiting toxicity and occurred in 93% of the dogs. Epithelial toxicity manifested as dermatitis, ulceration at friction sites, onychoptosis and alopecia also occurred in 70% of the animals. Hematologic changes and hepatotoxicity were minor and reversible, while dose-rlated anorexia and up to 60% weight loss were observed. Serum globulin changes in 2 dogs treated with 5.0 mg/kg included an increased α 2 level, a decreased α 1 level, and appearance of a second α 1 electrophoretic band. Severe nephrosis and/or nephritis also occurred in dogs treated with 2.5 or 5.0 mg/kg and contributed to the moribund condition of both dogs treated with the largest dose. Comparison of major toxic changes and clinical conditions. of the animals indicated that the primary toxicity was not identified. Preliminary results indicated that bleomycin may have affected cellular sulfhydryl or disulfide groups or availability of essential metals in those organs that concentrated the compound.

Effects of Δ9-tetrahydrocannabinol administered subcutaneously to rabbits for 28 days☆

Subcutaneous (s.c.) administration of delta-9-tetrahydrocannabinol (delta-9-THC) to rabbits produced dose-related cumulative toxicity. Five groups of three New Zealand albino rabbits each received 28 daily treatments with isotonic saline, sesame oil of 15.9, 45.0 or 153.4 mg/kg/day of delta-9-THC dissolved in sesame oil. Dose-related dermal responses included erythema, edema, ulceration and nodule formation. Some of the granulomatous nodules contained an oily substance and exhibited liquefactive necrosis. The severities of erythema and ulceration were generally maximal during the first week of treatment, but edema and nodule formation were most severe after days 12 and 14, respectively. All rabbits survived treatment, but body weights, liver weights and liver glycogen levels were decreased in a dose-related manner. Maximal body weight effects occurred after day 19. Hemochemical changes occurred only in rabbits treated with 153.4 mg/kg/day and included decreased blood sugar and alkaline phosphatase, and increased serum potassium. Hematology parameters were normal throughout the treatment period. No drug-related pathological lesions occurred in internal organs. The cumulative body weight changes, significantly decreased hepatic glycogen levels and reduced blood sugar and alkaline phosphatase values may have indicated drug-induced metabolic changes.

Pathological effects of bleomycin on the skin of dogs and monkeys

Bleomycin, an antitumor antibiotic with specific activity against squamous cell tumors of the skin, was administered iv every 4 days for 11 or 31 treatments to 14 dogs (0.156–5 mg/kg/day) and 11 monkeys (0.5–8 mg/kg/day). Severe doserelated cutaneous toxicity included dermatitis, ulceration at pressure and friction sites, onychoptosis and focal alopecia. Foot pads of dogs housed in wire floor cages were more severely affected than those housed on solid floors. In dogs, lesions occurred only on footpads and the tail tip, while in monkeys the neck, elbows, cubital fossa, ischial callosities and palmar and plantar surfaces of the hands and feet were affected. Microscopic changes at pressure and friction sites included ulceration, focal necrosis, subacute inflammation, hemorrhage, edema and occasional foreign body granulomas. Collagen bundles at both pressure and non-pressure sites showed increased homogeneity, but elastic and reticular fibers showed no evident abnormalities. Atrophy of sweat glands and pilosebaceous apparatus was also observed. Previously reported depression of serum zinc concentrations correlated with the onset of skin lesions, and suggested that zinc deficiency played a role in the pathogenesis of the lesions. Integumentary lesions at pressure and friction sites were a good visual index of bleomycin toxicity.

Azaserine-induced pathology in dogs☆

Abstract Administration of azaserine, acid-degraded azaserine and ethyldiazoacetate to dogs using various doses and routes resulted in pathologic changes only from azaserine. Graded doses of azaserine varying from 20 to 50 mg/kg were administered to 10 dogs by iv infusion, 6 dogs by po gelatin capsules and 3 dogs by gavage. Acid degraded azaserine was given in single doses of 30 mg/kg to 2 sex-paired dogs via 5 hr iv infusions and to 2 dogs by gavage. Ethyldiazoacetate, an analog of azaserine, was given by iv infusion of 19.8 mg/kg to 2 dogs. Two control dogs received iv infusion of 0.1 m phosphate-buffered saline at pH 7.5, and 2 dogs received no treatment. Major sites of azaserine-induced pathology were in kidneys, prostate and salivary glands. Prostatic lesions occurred in 50% of the animals and included necrosis, atrophy and squamous metaplasia. Mandibular salivary gland lesions occurred in 89% of the animals in included necrosis, atrophy, sialoadenitis and a decrease in sulfated mucopolysaccharides. The affected tissues are all known to contain an enzyme active in the degradation of azaserine. The selective toxicity in these organs suggested that azaserine might have clinical potential for treatment of salivary gland and prostatic tumors.

Phenester (NSC-116 785): Convulsant effects in the dog of an alkylating agent with antitumor activity☆☆☆★

Abstract Phenester [acetic acid, (p-(bis (2 chlorethyl)-amino)-phenyl) ethyl ester] is known to produce marked oncolytic activity against the mammary adenocarcinoma 13,762 in rats. For evaluation of toxicity, 17 dogs were treated with single doses of 120, 80, 20, or 5 mg/kg, with 5 consecutive daily doses of 80, 28, 14, 7, or 3.5 mg/kg, or with 11 treatments of 7 mg/kg, at 4-day intervals. The essential toxicity consisted of centrally induced salivation, vomiting, muscle twitches, tremors, and finally clonic and tonic convulsions. EEG recordings (2 dogs) from the thalamus and cerebral cortex demonstrated subcortical and cortical spikes and 3–4 cps hypersynchronous slow waves which during tonic convulsions, progressed into cortical and subcortical seizures followed by postictal silence. Six of the 8 dogs that developed tonic convulsions died or became moribund during the seizures or a few days thereafter. Mortality resulted from treatment with up to 5 daily doses of 28 mg/kg ( 2 2 ), 14 mg/kg ( 1 2 ), or 7 mg/kg ( 2 5 ). The other dogs survived. Tonic convulsions were also noted in one of 2 dogs receiving 11 treatments at 4-day intervals with 7 mg/kg/day, and in 1 dog treated with a single dose of 80 mg/kg. Dogs treated with 5 daily doses of 3.5 mg/kg or with a single dose of 20 mg/kg did not manifest convulsions. The 6 dogs which became critically ill exhibited very severe or severe hypocellularity of the bone marrow ( 5 6 dogs), severe hypocellularity of the lymphoid tissues ( 6 6 dogs), severe bronchopneumonia ( 2 6 dogs) or intestinal toxicity ( 1 6 dogs). Hepatic and renal toxicity were negligible. In contrast to other alkylating agents, phenester failed to produce degenerative changes of the spermatogenic cells or important intestinal histopathologic changes; convulsive properties predominated. Treatment with 3.5 mg/kg/day for 5 consecutive days elicited vomiting, but was otherwise tolerated without adverse side effects (maximum tolerated dose).