A patient with cancer developed extreme degree of radiation toxicity. Fuher history revealed that the dose adjustment of a paicular drug was missed during the course of radiotherapy. Which of the following drugs required a dose adjustment during radiotherapy in order to prevent radiation toxicity?

Actinomycin D (Dactinomycin) It is a very potent antineoplastic drug, highly efficacious in Wilms&; tumour and rhabdomyosarcoma. It has also produced good results in Mtx resistant choriocarcinoma and few other malignancies. Prominent adverse effects are vomiting, stomatitis, diarrhoea, erythema and desquamation of skin, alopecia and bone marrow depression. Medication orders for dactinomycin are commonly written in MICROgrams (eg, 150 mcg) although many regimens list the dose in MILLIgrams (eg, mg/kg or mg/m2). The dose intensity per 2-week cycle should not exceed 15 mcg/kg/day for 5 days or 400-600 mcg/m2/day for 5 days. The manufacturer recommends calculation of the dosage for obese or edematous adult patients on the basis of body surface area in an effo to relate dosage to lean body mass. Dactinomycin is associated with a high emetic potential; antiemetics are recommended to prevent nausea and vomiting. REFERENCE: ESSENTIALS OF MEDICAL PHARMACOLOGY(K.D.TRIPATHI,SIXTH EDITION,PAGE NO:826), www.drugs.com