Interaction of cimetidine but not ranitidine with cyclophosphamide in mice.

A series of experiments in DBA/2J mice evaluated the biological and pharmacokinetic interactions of the alkylating agent cyclophosphamide (CTX) and the histamine-H2 antagonists cimetidine (CMT) and ranitidine (RNT). Doses were adjusted to approximate human dose levels: 100 mg/kg for CMT; and 25 mg/kg for RNT. CMT reduced the survival of normal (bone marrow stem cell) colony forming units in a dose dependent fashion. CMT, given 5 or 30 min before CTX (200 mg/kg), significantly increased the survival of leukemia bearing mice, as well as the elimination half-life and plasma area under the curve of total alkylating metabolites of CTX. RNT did not significantly alter CTX antileukemic activity, pharmacokinetics, or toxicity to normal bone marrow stem cells. These results suggest caution in the use of CMT in patients being treated with CTX in order to avoid the possibility of exaggerated CTX toxicities. RNT may comprise a safer histamine-H2 antagonist to use with CTX if a histamine-H2 antagonist is clinically indicated.

Antitumor activity and murine pharmacokinetics of parenteral acronycine.

The lipophilic antitumor alkaloid acronycine (ACRO) was solubilized in the cosolvent system used for etoposide. ACRO in this etoposide diluent (VPD) was found to be cytotoxic (less than or equal to 50% colony formation in soft agar) in fresh human tumors from patients with renal cell cancer, ovarian cancer, uterine cancer, and metastatic tumors of unknown primary. In P-glycoprotein-positive, multidrug-resistant (MDR) cell lines, ACRO in VPD was active in MDR Chinese hamster ovary cells but not against MDR L1210 murine leukemia cells, 8226 human myeloma cells, or human CCRF-CEM lymphoblasts. In mice, ACRO in VPD was active in two solid tumor models and an i.p. MOPC-315 plasmacytoma model. ACRO i.p. in 10% VPD (v/v%) produced significant tumor growth delays in (a) nude mice bearing human MCF-7 breast cancer xenografts and (b) C57BL mice bearing colon 38 tumor. In MOPC-315-bearing mice, a single i.p. ACRO dose of 25 mg/kg was as effective as melphalan (15 mg/kg) at prolonging life span. Finally, ACRO pharmacokinetics was evaluated in mice given single 25-mg/kg doses i.p. or p.o. The oral bioavailability of an ACRO solution in VPD was only 50% but both i.p. and p.o. regimens achieved plasma levels greater than 1.0 micrograms/ml. The plasma half-life was just under 2 h. These results show that parenteral ACRO in VPD comprises a cytotoxic antitumor agent with improved bioavailability over p.o. administration. ACRO is active in vitro against several human solid tumors but is cross-resistant in 3 of 4 MDR tumor cell lines. The prior clinical activity of p.o. ACRO in myeloma and the new results in MOPC-315 plasmacytomas in mice suggest that ACRO in VPD could have activity against human multiple myeloma.

Mitomycin C skin toxicity studies in mice: reduced ulceration and altered pharmacokinetics with topical dimethyl sulfoxide.

A series of toxicologic and pharmacokinetic studies were performed in BALB/c mice administered intradermal (ID) mitomycin C (MMC) at doses of .015 to 0.25 mg. Dose-dependent skin ulcers were produced at clinically relevant MMC dose levels of .05 and .075 mg (3.6 to 10.7 mg/m2). These doses produced peak ulcers of 0.15 to 0.22 cm2, respectively, one to five days after injection. The integrated ulcer area X time values (area under the curve [AUC] ulceration) were 0.89 and 3.11 cm2 X d. A large number of local pharmacologic adjuvants were found to be ineffective at reducing MMC ulceration after proximal ID injection. These included diphenhydramine, catalase, heparin, hyaluronidase, hydrocortisone, cysteine, N-acetylcysteine, lidocaine, vitamin E, and superoxide dismutase. Also, neither topical heating nor cooling of skin reduced MMC ulcerations. In contrast, a single topical application of a 100% dimethyl sulfoxide (DMSO) solution completely prevented 0.025 mg MMC-induced skin ulceration and significantly reduced .075 mg MMC ulceration (P less than .05 by multiple range tests). Topical DMSO also altered the disposition of ID MMC in mouse skin but not in plasma. Unexpectedly, the DMSO applications slowed MMC elimination from the skin. DMSO significantly increased the AUC for MMC in skin from 0.89 to 2.25 ng/h/mL of tissue (P less than .05). DMSO did not alter the degree of protein binding in skin tissue nor the in vitro chemical stability of MMC in skin tissue homogenates. These results show that experimental MMC-induced skin ulcers in mice can be ameliorated with an immediate application of topical DMSO. This effect is not due to enhanced systemic drug uptake, but may be due to reduced reactivity of MMC with target cellular nucleophiles.

The effect of glutathione (GSH) depletion in vivo by buthionine sulfoximine (BSO) on the radiosensitization of SR 2508.

The effect of glutathione depletion (GSH) on the efficacy of SR 2508 was evaluated in two murine tumor models with single large doses of radiation or with low doses administered in an accelerated fractionated schedule. To deplete tumor GSH, buthionine sulfoximine (BSO) was administered in the animals drinking water (10 mM) following two i.p. injections of 450 mg/kg. This treatment decreased RIF and MCA tumor GSH concentrations by 95% and 80%, respectively. Mice (C3H/Sed) received BSO for 48-72 hr before the first dose of radiation, and were maintained on BSO drinking water for the duration of the fractionated course of therapy. SR 2508 (200-1000 mg/kg) was injected 45 min prior to each fraction of radiation. Radiation was administered as a single dose of 15 Gy or 20 Gy, for RIF and MCA tumors, respectively. Alternatively, animals received a fractionated course of radiotherapy which consisted of 2.5 Gy/fraction for the RIF, and 3 Gy/fraction for the MCA tumors, b.i.d. for five days (total of 10 fractions). Tumor response with and without BSO, and with and without SR 2508, was determined by regrowth delay. BSO pretreatment increased the efficacy of SR 2508 with single dose radiation in the MCA but not RIF tumor. SR 2508 administered with fractionated radiation produced lower enhancement ratios (SER) than with a single radiation dose. However, BSO significantly enhanced the efficacy of SR 2508 with fractionated radiation. BSO increased the maximum SER for SR 2508 (3 mM/fraction) from 1.2 to 1.4 in the RIF tumor, and from 1.4 to 1.8 in the MCA tumor. BSO also increased the toxicity of SR 2508 by a factor of 2. However, the ability of BSO to increase the efficacy of low doses of sensitizer at clinically relevant doses of radiation suggests that this combined modifier treatment may be of clinical benefit.

Cimetidine enhances cisplatin toxicity in mice.

The combination of the histamine H2 antagonist cimetidine (CMT) and the anticancer agent cisplatin (CDDP) was studied in normal and tumorbearing mice. CMT doses of 100 mg/kg produced no alteration in the survival of DBA/2J mice bearing P388 leukemia treated with CDDP doses of 3 mg/kg or 6 mg/kg. In these groups, the median survival was 13 days and 16 days, respectively, compared to 10 days in untreated controls. However, when adult CD-1 mice were given higher but nonlethal CDDP doses of 10, 15, or 18 mg/kg, the addition of CMT significantly increased CDDP lethality (P less than 0.05 by Wilcoxon analysis). For the 3 groups, CMT-enhanced lethality occurred in 10% of mice given 10 mg/kg CDDP, 80% of mice given 15 mg/kg, and 100% of mice given 18 mg/kg CDDP. Thus, CMT can acutely alter CDDP toxicity without affecting antitumor efficacy in mice.

H2-antagonists and carmustine.

The highly metabolized nitrosourea carmustine (BCNU) is an anticancer agent which alkylates DNA and is metabolized to both active and inactive species by cytochrome P-450 enzymes. Other highly metabolized anticancer drugs have altered toxicities when some histamine H2 antagonists are coadministered. To test this hypothesis with BCNU, DBA/2J male mice were given a single injection of cimetidine (CMT 100 mg/kg) or ranitidine (RNT 25 mg) at various times up to 30 min before, or up to 60 min after a BCNU injection. Spleen colony assays for normal bone marrow stem cell viability showed enhanced toxicity for BCNU when CMT was administered concomitantly. In P-388 leukemia-bearing DBA/2J mice, both CMT and RNT significantly enhanced the antitumor effects of BCNU doses of 30 mg/kg. Pharmacokinetic analyses of BCNU elimination in Cd-1 mice showed marked prolongation of BCNU elimination and increased (BCNU concentration) x time products when CMT was concomitantly administered. These results demonstrate that enhanced BCNU bone marrow toxicity and antitumor activity is produced by CMT. The effect appears to be related to impaired drug clearance when the two agents are administered concurrently. RNT slightly enhanced BCNU antileukemic effects, but it did not significantly alter BCNU myelotoxicity nor drug elimination patterns.

Efficacy of sodium thiosulfate as a local antidote to mechlorethamine skin toxicity in the mouse.

The highly vesicant nature of the alkylating anticancer agent mechlorethamine (HN2, or nitrogen mustard) requires careful i.v. technique during its administration. Skin toxicity due to HN2 extravasation is severe and typically prolonged over several months. Mouse skin toxicity studies were carried out to find a local antidote to decrease the severity of tissue damage by this agent. Intradermal (i.d.) HN2 (0.005-0.5 mg) caused dose-dependent skin ulcers in the mouse. Isotonic sodium thiosulfate Na2S2O3 (0.167 M) or hypertonic (0.34 M) Na2S2O3 (0.05 ml) given immediately after HN2 significantly reduced the mean HN2 ulceration area and the total time of ulceration. Ineffective local HN2 antidotes included hyaluronidase, hydrocortisone, and sodium chloride, all given i.d. Topical applications of DMSO, cold, and heat were also ineffective. Sodium thiosulfate is believed to chemically neutralize reactive mechlorethamine-alkylating species and thus decrease skin toxicity. Thiosulfate dosing studies showed that a molar excess of at least 200:1 (Na2S2O3:HN2) was required for significant antidotal activity. If thiosulfate treatment was delayed 4-24 h after HN2, no antidotal effects were obtained. We conclude that sodium thiosulfate can decrease the severity of local tissue damage caused by HN2. It should be considered the antidote of choice in the setting of clinical HN2 extravasations.

Lack of experimental vesicant activity for the anticancer agents cisplatin, melphalan, and mitoxantrone.

Cisplatin and L-PAM are DNA-crosslinking anticancer agents which have not been systematically studied for vesicant potential. Mitoxantrone is a new active anthracene-based, DNA intercalator which is undergoing widespread clinical testing for antitumor efficacy in man. These three agents were tested for vesicant activity in dehaired BALB/c mice given ID injections equivalent to human clinical doses. Neither cisplatin (up to 150 mg/m2) nor L-PAM (up to 71 mg/m2) produced any skin necrosis in the mice. The L-PAM solvent (acid/alcohol in propylene glycol) was ulcerogenic if injected undiluted. Mitoxantrone (up to 14 mg/m2) was not ulcerogenic in the mice, although the skin site retained a blue drug discoloration for several weeks. It is concluded that in clinically relevant doses, cisplatin, L-PAM, and mitoxantrone are not vesicants.

Dose-dependent skin ulcers in mice treated with DNA binding antitumor antibiotics.

The DNA-binding agents daunomycin (DAU-NO), mithramycin (MITH), dactinomycin (ACT-D), amsacrine (mAMSA) and esorubicin (ESO) were tested for local vesicant potential in a quantitative intradermal mouse skin model. Only MITH, which adlineates but doses not intercalate DNA, did not produce dose-dependent skin ulcerations in the mouse. The anthracycline antibiotics DAUNO and ESO produced the largest skin ulcers when administered intradermally at clinically relevant doses (adjusted on the basis of comparable body surface areas). Numerous local pharmacologic adjuvants were tested for activity to decrease skin ulceration patterns in mice given one of the DNA intercalators. Inactive local adjuvants included heat, cold, saline, hyaluronidase, glucorticosteroids and isoproternol. Only one adjuvant, topical dimethylsulfoxide (DMSO), was found to reduce DAUNO skin lesions. A single topical DMSO application significantly decreased ulceration size to almost half of control levels. However, it was ineffective for the other intercalating agents. These results show that the DNA intercalators DAUNO, ESO and ACT-D are potent vesicants in a mammalian skin model. These vesicant agents must be administered cautiously to prevent extravasation. No single local adjuvant treatment can be recommended for extravasation of these drugs in the clinic. One significant exception is DAUNO, where topical DMSO may reduce clinical toxicities.

Hairy cell leukemia presenting as localized skeletal involvement.

We report a 45-year-old man who presented with localized skeletal involvement as the initial manifestation of hairy cell leukemia (HCL) without abnormal peripheral blood counts, splenomegaly or posterior iliac crest bone marrow involvement. The patient presented with pain in the left thigh. A plain radiograph was normal, but a magnetic resonance imaging (MRI) of this region showed a marrow-based lesion occupying the left femur neck, left proximal femur and both greater trochanters. Histological and immunophenotypic examination revealed a focal infiltrate of HCL. Skeletal involvement by HCL without co-existing bone marrow involvement should be included in the differential diagnosis of bone marrow lesions where metastatic tumor is the foremost consideration.

Lack of enhanced antitumor efficacy for L-buthionine sulfoximine in combination with carmustine, cyclophosphamide, doxorubicin or melphalan in mice.

A series of studies was performed in tumor bearing mice to evaluate the impact of glutathione (GSH) depletion by L-buthionine sulfoximine (L-BSO). L-BSO doses of 50 or 500 mg/kg were used alone or with one of 4 sulfhydryl-dependent anticancer agents (SHDAA). When L-BSO was administered to tumor-bearing mice, Colon 38 cells were significantly depleted of GSH content, but this did not occur with P388 cells or MOPC-315 cells in vivo. GSH levels in these ascites tumors declined significantly without L-BSO treatment as the tumor rapidly grew in the IP space. SHDAAs, including doxorubicin (DOX), cyclophosphamide (CTX), carmustine (BCNU) and melphalan (L-PAM) were then combined with L-BSO in mice bearing P388, MOPC-315 or colon 38 tumors. There was no consistent enhancement of antitumor efficacy using a treatment interval of 24 hrs (L-BSO given first). In contrast, there was some evidence of significantly enhanced SHDAA toxicity with L-BSO. Further studies should evaluate different dosing intervals to take advantage of the slower rate of GSH replenishment observed in normal tissues compared to solid tumor cells (Colon 38) in vivo. In addition, significant reductions for any SHDAA combined with L-BSO are indicated in any such trial.

Lack of enhanced myelotoxicity with buthionine sulfoximine and sulfhydryl-dependent anticancer agents in mice.

The lethal and non-lethal effects of L-buthionine-SR-Sulfoximine (BSO) with the sulfhydryl-dependent anticancer agents (SHDAA) were investigated in mice. The agents studied included carmustine (BCNU), cyclophosphamide (CTX), doxorubicin (DOX) and melphalan (LPAM). It was shown in normal mice that BSO is nontoxic when given IP or PO at a dose 5 g/kg. In pharmacodynamic studies with two different doses of BSO in CD-1 mice, the liver, kidney and heart demonstrated diurnal variations in thiol content and dose-dependent depression of tissue non-protein sulfhydryl (NPSH) levels. In acute lethal survival studies, mice treated with CTX and BSO exhibited increased lethality with seizures as a possible cause of death. This effect was not seen with BCNU, DOX and LPAM. Evaluations of organ-specific biochemical markers, showed slight elevations in LDH enzyme levels while bone marrow suppression was not enhanced using both in vivo spleen colony assay and in vitro colony forming unit myelotoxicity assays. These results show that the addition of BSO with SHDAA enhances the acute lethality of some agents such as CTX, and may also increase the non-myelosuppressive toxicities of other agents. It is recommended that BSO be used with caution in combination with SHDAA and that monitoring of hepatic enzymes be routinely performed.

Rotator cuff tear: clinical experience with sonographic detection.

Between June 1986 and April 1988, 86 sonographic examinations of the shoulder were performed on patients suspected of having rotator cuff tears. Major sonographic diagnostic criteria included (a) a well-defined discontinuity usually visible as a hypoechoic focus within the cuff, (b) nonvisualization of the cuff and (c) an echogenic focus within the cuff. Seventy-five patients underwent both sonography and arthrography. Compared with arthrography alone, ultrasound examinations enabled detection of 92% of rotator cuff tears (24 of 26 tears), with a specificity of 84% and a negative predictive value of 95%. Correlation was obtained in 30 of these patients who underwent surgery for rotator cuff tear or other soft-tissue abnormality. In this group, the sensitivity of sonography for detection of a tear was 93%, with a specificity of 73%, while for arthrography sensitivity was 87% and specificity was 100%. These data indicate that sonography is a useful, noninvasive screening procedure for patients suspected of having rotator cuff injury.

Cytotoxic effects of glutathione synthesis inhibition by L-buthionine-(SR)-sulfoximine on human and murine tumor cells.

The glutathione (GSH) synthesis inhibitor, buthionine sulfoximine (BSO) was tested for cytotoxicity and thiol depletion in murine and human tumor cells in vitro, and for its antitumor activity and toxicity in vivo. The cell lines used in these studies included murine L-1210 leukemia, human RPMI 8226 myeloma, MCF-7 breast cancer and WiDr colon carcinoma. Soft agar colony forming assays showed that BSO was most effective at reducing tumor colony formation when exposed continuously to cells in vitro. Drug concentrations which inhibited colony formation to 50% of control levels ranged from 2.0-6.2 mM (for 1 hour exposures), 2-100 mM for 24 hour exposures and 0.4-1.40 microM (for continuous BSO exposures). Human myeloma cells proved most sensitive to BSO. In vitro cytotoxicity correlated with depletion of intracellular nonprotein sulfhydryls to less than or equal to 10% of control values in both L-1210 and 8226 cells. This was routinely achieved with prolonged exposures to mM BSO concentrations for greater than 24 hours. Normal mice tolerated high BSO doses (up to 5.0 g/kg) without evidence of acute toxicity. BSO was not active against L-1210 leukemia-bearing DBA/2 mice. When tested in vivo against MOPC-315 plasmacytoma-bearing BALB/c mice, BSO was not active at doses up to 4.0 g/kg. In contrast, the bifunctional alkylating agent melphalan (L-PAM) was active against MOPC-315 and this activity was enhanced by a 24 hour pretreatment of mice with 50 mg/kg of L-BSO.(ABSTRACT TRUNCATED AT 250 WORDS)

Ethanol increases opioid activity in plasma of normal volunteers.

The effect of acute ethanol administration on plasma levels of beta-endorphin-immunoreactivity and opioid activity was measured in 4 normal volunteers. 60 min following ethanol consumption opioid activity levels, measured by radioreceptorassay, increased significantly with peak rises of more than 400%; levels of beta-endorphin-immunoreactivity did not change significantly. These results are compatible with the effect of the opiate-antagonist naloxone, reversing ethanol-induced coma.

Experimental dacarbazine antitumor activity and skin toxicity in relation to light exposure and pharmacologic antidotes.

Decarbazine (DTIC) is reported to exhibit enhanced clinical toxicity and increased antitumor activity in vitro when exposed to light. Since it was unclear whether light exposure enhanced DTIC antitumor activity or local toxic effects in vivo, a series of experiments was performed in mice given DTIC solutions exposed to light for 2 hours at room temperature. Adenocarcinoma 07/A was implanted by trocar in adult female BALB/c mice. DTIC (50 and 100 mg/kg) was given ip three times per week for 2 weeks. Both drug doses significantly inhibited tumor growth. However, there was no significant difference between light-exposed and -protected drug treatments. In vitro clonogenic assays in L1210 leukemia and Chinese hamster ovary (CHO) cells demonstrated that DTIC cytotoxicity was not increased with light exposure (0.8 J/m2/sec). Both cell lines showed a dose-response relationship to DTIC after 1- or 6-hour exposures in the presence or absence of light. Normal dehaired BALB/c mice were given single intradermal injections of 0.5, 1.75, 5.0, or 10 mg of DTIC in 0.05 ml of saline. Dose-dependent skin ulceration was produced at the 1.75-, 5.0-, and 10.0-mg dose levels. Again, there was no consistent statistical difference in skin ulceration between treatments using light-exposed and -protected DTIC vials. However, when mice were exposed to light following intradermal DTIC, increased skin toxicity was produced (P less than 0.05 by Student-Neuman-Keuls multiple range test). A number of potential local antidotes to DTIC skin ulceration were found to be ineffective. These included: L-cysteine, dimethyl sulfoxide, hyaluronidase, hydrocortisone, and 0.9% saline. Sodium thiosulfate (0.3 M) significantly reduced DTIC skin ulcers as did pre-exposure of DTIC to S-9 rat liver enzymes and NADPH. Neither mild skin heating nor cooling reduced DTIC ulcerations. DTIC appears to synergize with light in vivo to produce increased toxicity. Patients receiving DTIC should avoid intense light exposure after drug injection. However, elaborate precautions to prevent light exposure of DTIC solutions during preparation or injection appear to be unnecessary.