Antitumor antibiotics: Nursing pharmacology

Antitumor antibiotics are chemotherapeutic agents used to treat various cancers, including leukemia, lymphoma, soft tissue sarcoma, osteosarcoma, as well as solid tumors, such as breast, bladder, ovarian, and lung cancers. Antitumor antibiotics include bleomycin, dactinomycin, mitomycin, as well as anthracyclines such as daunorubicin, doxorubicin, idarubicin, and epirubicin.

These medications are primarily given intravenously, but bleomycin can also be administered intramuscularly. Once administered they act as cell cycle nonspecific agents, which means they target cells in all phases of the cell cycle. The exception is bleomycin, which specifically goes for cells in the G2 phase. Now, the way they work is twofold: first, these medications disrupt protein synthesis in target cells; and second, they bind to DNA, causing its fragmentation. Ultimately, this stops the rapidly dividing cancer cells from replicating and eventually causes their death.

Unfortunately, antitumor antibiotics also act on rapidly dividing healthy cells in our body, like those in the bone marrow, skin, and gastrointestinal tract. So antitumor antibiotics, with the exception of bleomycin, can all cause bone marrow suppression, which is a boxed warning for all anthracyclines as well as mitomycin. Bone marrow suppression can lead to anemia, leukopenia, increasing the risk of infections, and thrombocytopenia, increasing the risk of bleeding. Moreover, they can all cause alopecia, as well as gastrointestinal toxicity, which can manifest as nausea, vomiting, diarrhea or stomatitis.

Another important thing to remember is that all these medications are vesicants, which means they can cause blistering and tissue damage if they leak from the administering site into neighboring tissues; and this is actually a boxed warning for all anthracyclines. Other important side effects include pulmonary toxicity, which can occur with bleomycin, dactinomycin and mitomycin, and cardiotoxicity cardiac toxicity, which is a boxed warning for all anthracyclines, and a common side effect of mitomycin. The good news is that cardiotoxicity can be reduced prevented with a medication called dexrazoxane.

Additionally, daunorubicin and idarubicin come with a boxed warning for dosage reduction in hepatic and renal impairment. The other two anthracyclines, namely doxorubicin and epirubicin, have boxed warnings for the risk of developing a secondary malignancy after prolonged use, and they can also cause a red discoloration of urine and sweat. And finally, some specifics. Bleomycin comes with a boxed warning for the risk of developing a reaction consisting of hypotension, fever, chills and confusion; and mitomycin can cause hemolytic uremic syndrome, which is when anemia, thrombocytopenia and acute kidney failure occur.

Dactinomycin can also cause nephrotoxicity and can potentiate the effects of radiotherapy; while mitomycin can cause cardiotoxicity. Antitumor antibiotics should not be used during pregnancy, lactation, or in clients with severe cardiac disease. These medications should also be used with caution in clients with hepatic and renal impairment. And now, for some specifics, bear in mind that doxorubicin should not be used at the same time as antifungal medications such as fluconazole, since that increases the cardiotoxic effect of doxorubicin and the subsequent risk of life threatening arrhythmias.

Mitomycin should not be used in people with thrombocytopenia or coagulation disorders, or in conjunction with NSAIDs, salicylates or oral anticoagulants, as that can increase bleeding risk. Finally, remember that doxorubicin and idarubicin are contraindicated after a recent myocardial infarction, people with myocardial insufficiency and arrhythmias; as well as in people with severe hepatic impairment or myelosuppression.

Now, when a client with breast cancer is prescribed an antitumor antibiotic like doxorubicin as part of their chemotherapy regimen, begin your assessment by reviewing your client’s current symptoms, including the presence of a hard, immovable lump in the breast or underarm, as well as nipple discharge, pain, and any skin changes on the breast or nipple.

Next, obtain your client’s weight and vital signs; review laboratory test results, such as CBC, renal and hepatic function; and confirm a negative pregnancy test as needed. Review any diagnostic test results, including mammogram, ultrasound, MRI, biopsy results, and baseline ECG. Lastly, confirm the assigned Tumor, Node, Metastasis or TNM classification of the tumor and calculate the prescribed dose in mg/m2.