Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment could also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

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Serious adverse interactions between drugs continue to be reported. Many of these are due to inhibition or induction of cytochrome P450 (CYP) enzymes, particularly CYP3A4. CYP3A is thought to be involved in the metabolism of more than 50 percent of currently prescribed drugs.2 CYP3A4, which is more abundantly expressed than CYP3A5, accounts for most CYP3A activity in vivo.

Aprepitant (Emend - Merck), the first substance P/neurokinin 1 (NK₁) receptor antagonist to be approved by the FDA, is now available for oral use with corticosteroids and selective serotonin (5-HT₃) receptor antagonists to prevent nausea and vomiting caused by highly emetogenic anticancer drugs such as cisplatin.

Changes caused by one drug in the absorption, distribution, metabolism or excretion of another may lead to a pharmacokinetic adverse drug interaction (DN Juurlink et al, JAMA 2003; 289:1652). Additive drug interactions, such as vasodilation caused by both sildenafil (Viagra) and nitrates, can also have adverse effects.

The tables in this article list drugs used for treatment of cancer in the USA and Canada and their major adverse effects. The choice of drugs in Table I is based on the opinions of Medical Letter consultants. Some drugs are listed for indications for which they have not been approved by the US Food and Drug Administration. In some cases, such as elderly patients or those with many co-morbid illnesses, the regimen of choice might not be suitable. For many of the cancers listed, surgery and/or radiation therapy may be the treatment of choice or may also be part of the management. Anticancer drugs and their adverse effects are listed in Table II on page 46. A partial list of brand names appears on page 52.

Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment may also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

The tables in this article list drugs used for treatment of cancer in the USA and Canada. The choices of drugs in Table 1 is based on the opinions of Medical Letter consultants. Some drugs are listed for indications for which they have not been approved by the US Food and Drug Administration. For many of the cancers listed, surgery and/or radiation therapy are also part of the management of the disease.

Vinorelbine (Navelbine - Burroughs Wellcome), a semisynthetic vinca alkaloid, has been approved by the US Food and Drug Administration for parenteral use in the treatment of advanced non-small-cell lung cancer (NSCLC). Various combinations of cisplatin (Platinol), vinblastine (Velban, and others), mitomycin (Mutamycin), ifosfamide (Ifex), etoposide (VePesid) and paclitaxel (Taxol) have been used previously for this indication.

Some commonly used systemic drugs that may cause pulmonary toxicity are listed in the table below. These adverse effects may sometimes be difficult to distinguish from the underlying disease (JAD Cooper, Jr et al, Am Rev Respir Dis, 133:321, 488, 1986). Pulmonary effects that are part of a generalized reaction or are indirect effects of drugs - on respiratory muscles, for example, or on the immune system - are not included here.

Ifosfamide (Ifex - Mead Johnson), a synthetic analog of cyclophosphamide (Cytoxan; and others), has been approved by the US Food and Drug Administration (FDA) for concurrent use with other drugs in third-line chemotherapy of metastatic germ-cell testicular cancer. Given concomitantly, a synthetic sulfhydryl compound known as mesna (Mesnex - Asta) acts in the urine to detoxify metabolites of ifosfamide that cause hemorrhagic cystitis (H Burkert, Cancer Treat Rev, 10 suppl A:175, 1983). Ifosfamide and mesna are available together from Bristol-Myers Oncology Division.