Chemotherapy prescribing

Every Monday in your oncology outpatient department, you run a pharmacist/ nurse-led oral capecitabine clinic, where patients are referred to you by oncologists for pretreatment counselling, drug history-taking and supplementary chemotherapy prescribing (under set clinical management plans) for the adjuvant treatment of colon cancer or treatment of metastatic colorectal cancer. 

Each organization should have chemotherapy safety checks built into the prescribing, preparation, and administration of chemotherapy.50 Dosing based on patient-specific body information should be included on every order for chemotherapy, whether it is oral or parenteral. Many chemotherapy regimens... 

Determine if any dose modifications are required in the chemotherapy regimen prescribed. Does the patient have adequate blood counts to receive chemotherapy ... 

Cyanide compounds have been prescribed by physicians for treatment of hypertension and cancer (Sprine et al. 1982). Sodium nitroprusside (Na2Fe(CN)5NO 2H20) was widely used for more than 30 years to treat severe hypertension and to minimize bleeding during surgery (Solomon-son 1981 Vesey 1987). Laetrile, an extract of ground apricot kernels, has been used for cancer chemotherapy and, in deliberate high intakes, as an attempted suicide vehicle (Gee 1987). 

The prototypical form of error in the health care system that could be reduced by a systems approach is medication error. The kind of error identified in the literature—overdose of chemotherapy, injection of the wrong drug, etc.—sometimes leads to either injury or death, the kinds of harm that are the central concern of after-the-fact medical liability adjudication. Phar-macogenomics introduces not only another conception of harm—genetic risks—but also new ways of developing and prescribing drugs. 

Some alternative therapies have even crossed the line into mainstream medicine, as scientific investigation has confirmed their safety and efficacy. For example, physicians may currendy prescribe acupuncture for pain management or to control the nausea associated with chemotherapy. Additionally, many U.S. medical schools teach courses in alternative therapies, and many health insurance companies offer some alternative medicine benefits. 

Erythropoietin Erythropoietin (EPO) (Fig. 4.8) is a glycoprotein produced by specialized cells in the kidneys. It has 166 amino acids and a molecular weight of approximately 36kDa.EPO stimulates the stem cells of bone marrow to produce red blood cells. It is used to treat anemia and chronic infections such as HIV and cancer treatment with chemotherapy where anemia is induced. Patients feel tired and breathless owing to the low level of red blood cells. EPO can be prescribed instead of blood transfusion. 

Many patients receive lengthy courses of antibiotics that probably should not have been started. More than half of courses of antimicrobial chemotherapy are inappropriate. Influenza pneumonia and viral upper respiratory infections, for example, are impervious to assault by antibiotics, although many patients with these illnesses receive such antibiotics. Of course, influenza may be complicated by postinfluenzal staphylococcal pneumonia, for which antibiotics are indicated. Careful sequential evaluation of seriously ill patients for whom antibiotics are deferred is as important as in patients for whom antibiotics are prescribed. 

A 65-year-old man with acute leukemia recently underwent induction chemotherapy and subsequently developed neutropenia and fever (with no source of fever identihed). Fever persisted despite the use of empirical antibacterial therapy, and amphotericin B has been prescribed for possible fungal sepsis. Which laboratory test is LEAST helpful in monitoring for toxicities associated with amphotericin B ... 

Dronabinol. Dronabinol is a synthetic form of THC that was approved for medical use by the FDA in 1985. Sold under the trade name Marinol, it is prescribed as an antiemitic for cancer patients undergoing chemotherapy and as an appetite stimulant for AIDS patients who become anorexic. Marinol is manufactured in 2.5-, 5-, and 10-mg capsules, which are taken orally. Critics argue that suppositories would be more useful than capsules since cancer and AIDS patients are often unable to keep food down. 

Courtney began by diluting chemotherapy drugs for patients who were near death. He started out by diluting the drugs only a bit, thinking no one would notice. Later, he became more bold and diluted medications to the point that only a trace of the prescribed dose remained. He started out cheating just a little and then slid down a slippery slope until he was convicted of his crimes and sentenced to 30 years in prison. As stated in a newspaper feature about his case ... 

Prompted by the early work with the artificial kidney by Dedrick and Bischoff [1], together with later applications to cancer chemotherapy, considerable effort has been made to develop analytical models to describe the transient fate of solutes within physiological systems. Experimental measurements obtained in laboratory animals have been used to develop a set of scaling rules useful for extending these results to humans. These models describe the time course of solutes that are either being removed or injected according to a prescribed temporal pattern. 

Briefly describe some of the key principles in the prescribing and dispensing of oral chemotherapy. 

Mrs RP returns to your clinic three weeks later for her second cycle, having completed her two-week course of capecitabine with a week s break. She states that she tolerated the chemotherapy very well apart from some diarrhoea - she suffered from nocturnal episodes on three consecutive nights during treatment. You also notice that she has brought back empty boxes of capecitabine from her first cycle, indicating that she finished her treatment as prescribed. 

Mrs RP wonders why her GP cannot prescribe her chemotherapy as she lives just around the corner from him. What do you say to her ... 

This can be controlled with the co-administration of standard antidiarrhoeal agents such as loperamide. All patients on FOLFOX chemotherapy (or any 5-fluorouracil-containing regimen) should be co-prescribed an antidiarrhoeal medication to use on an as required basis. The onset of diarrhoea should also indicate to the patient that they must increase their fluid intake to prevent dehydration. Patients must be warned that if the diarrhoea is not controlled (for example, within 48 hours of onset) then dehydration is a danger and they should be advised to contact their treating hospital or GP for advice. Severe manifestations may have to be managed by delay and/or dose modification of the patient s next cycle of chemotherapy. 

Many clinicians prescribe pyridoxine tablets or cream to manage this side-effect, however the evidence for this treatment is scarce. Severe manifestations may have to be managed by delay and/or dose modification of the patient s next cycle of chemotherapy (only the 5-fluorouracil component need be dose modified). 

Apart from basic information such as name of drug, its purpose (laxative) and the dose and frequency it should be taken, it is important to impress on Mrs CR the necessity to not increase the dose beyond that prescribed unless recommended by her GP or hospital doctor. Unless she was to develop diarrhoea (which is possible while on chemotherapy treatment), she should be counselled to continue taking senna while on morphine treatment. 

If it is agreed that the dose should be reduced at this cycle, a review should occur immediately prior to the next cycle of chemotherapy before the next dose is prescribed. As the renal impairment is likely to be due to the presence of tumour compressing the ureters, a significant improvement in renal function would be expected should the disease respond to treatment and the dose of cisplatin should therefore be able to be increased back to 100%. Close monitoring of the renal function (serum urea, creatinine and EDTA clearance) is therefore essential. 

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