Cyclosporin A and doxorubicin-ifosfamide in resistant solid tumours: a phase I and an immunological study

Drug-induced hypomagnesaemia : scope and management

Nearly 50 medications have been implicated as inducing hypomagnesaemia, sometimes based on insufficient data regarding clinical significance and frequency of occurrence. In fact, clinical effects attributed to hypomagnaesemia have been reported in only 17 of these drugs. A considerable amount of literature relating to individual drugs has been published, yet a comprehensive overview of this issue is not available and the hypomagnesaemic effect of a drug could be either overemphasised or under-rated. In addition, there are neither guidelines regarding treatment, prevention and monitoring of drug-induced hypomagnesaemia nor agreement as to what serum level of magnesium may actually be defined as 'hypomagnesaemia'. By compiling data from published papers, electronic databases, textbooks and product information leaflets, we attempted to assess the clinical significance of hypomagnesaemia induced by each drug. A practical approach for managing drug-induced hypomagnesaemia, incorporating both published literature and personal experience of the physician, is proposed. When drugs classified as inducing 'significant' hypomagnesaemia (cisplatin, amphotericin B, ciclosporin) are administered, routine magnesium monitoring is warranted, preventive treatment should be considered and treatment of hypomagnesaemia should be initiated with or without overt clinical manifestations. In drugs belonging to the 'potentially significant' category, among which are amikacin, gentamicin, laxatives, pentamidine, tobramycin, tacrolimus and carboplatin, magnesium monitoring is justified when either of the following occurs: clinical manifestations are apparent; persistent hypokalaemia, hypocalcaemia or alkalosis are present; other precipitating factors for hypomagnesaemia coexist; or treatment is with more than one potentially hypomagnesaemic drug. No preventive treatment is required and treatment should be initiated only if hypomagnesaemia is accompanied by symptoms or clinically significant relevant laboratory findings. In those drugs whose hypomagnesaemic effect is labelled as 'questionable', including furosemide and hydrochlorothiazide, routine monitoring and treatment are not required.

Adriamycin cytotoxicity may stimulate growth of hepatocellular tumours in an experimental model for adjuvant systemic chemotherapy in liver transplantation

Adjuvant treatment with adriamycin has been suggested to improve results after liver transplantation for hepatocellular cancer. Here we have applied an animal model for evaluation of treatment with adriamycin and/or cyclosporine A on liver tumour growth. Three chemically induced rat liver tumours with various degree of differentiation were transferred to the spleens of syngenic rats. Each recipient group was divided into four subgroups, treated with adriamycin and/or cyclosporine A or none of the drugs. When the tumour was well differentiated no proliferation was found in any of the subgroups. When the tumour exhibited a more pronounced dysplasia, adriamycin stimulated tumour growth. This effect was further increased by cyclosporine. In the animals transplanted with the most aggressive tumour, adriamycin inhibited tumour growth. When given together with cyclosporine this inhibition was counteracted. These data suggest that adriamycin, especially when given together with cyclosporine, may have a stimulatory effect on liver tumour cell growth.

Cyclosporin A enhances locoregional metastasis of the CC531 rat colon tumour

The immunosuppressive drug cyclosporin A has been evaluated recently in phase II trials in cancer therapy as a reverter of P-glycoprotein-mediated multidrug resistance. As an immunosuppressive agent, cyclosporin A potentially can enhance tumour growth. We investigated this potency of cyclosporin A in the weakly immunogenic CC531 colon adenocarcinoma model, using the same dose that had previously been shown to intensify the antitumour activity of doxorubicin in vivo. In vitro cyclosporin A caused no growth acceleration and only in high doses was growth inhibition of CC531 cells observed. In vivo no evidence of growth enhancement was found in short-term assays but, after 4 weeks, rats treated with cyclosporin A had a significantly higher tumour load, mainly consisting of locoregional metastases. These experiments in the CC531 tumour model show that cyclosporin A, used as a reverter of multidrug resistance, may produce short-term improvement of antitumour activity but may also induce enhancement of tumour metastasis.