Anticancer Drugs Pharmacology
Introduction
Learning about anticancer drugs pharmacology is challenging. There are many drug classes, each of which with members that often have wildly different indications, side effects and drug interactions.
As part of your pharmacy exam, you can expect a reasonable sample of questions on chemotherapy. To do well, you need to be prepared. First, you must organize your study of how you intend to commit the relevant details to memory.
Below, for example, we put together a near complete database of anticancer drug classes, members and mechanisms of action. We’ve also included some ancillary detail where necessary. These details should be the very minimum you know.
From there, learn more about chemotherapy regimens – what drugs are included and why. Think about dosage factors, too, and how different dosages are put together depending on the patient and their form/stage of cancer treatment.
That’s because anticancer drugs are not used in isolation. Take a glance at some of the most widely known chemotherapy regimens:
- CHOP–cyclophosphamide, doxorubicin, vincristine, prednisolone.
Used in the treatment of non-Hodgkin’s lymphoma. - FOLFOX – 5-fluorouracil, folinic acid, oxaliplatin.
Used in the treatment of colorectal cancer. - FLAG – fludarabine, cytarabine, G-CSF.
Used in the treatment of acute myelogenous leukemia
There are many, many more – but these three give you a solid idea.
Side Effects of Anticancer Drugs
In addition to learning about drug mechanisms and dosages, think about prominent side effects, too.
It takes practice, often lots of it, to commit anticancer side effects to memory. There is no one simple solution. The best way is to compile a list of the most serious side effects and commit those first to memory.
Build on that list over time, often with tangential side effects. In time, your mental database of side effects will build and build and build – to the point where it becomes second nature. At that point, you can expect to do very well on this section of your NAPLEX exam.
Here is a list of 16 prominent anticancer drug-side effects to start you off:
| Anticancer Drug | Notable Side Effect(s) |
|---|---|
| Irinotecan | Severe diarrhea |
| Cyclophoshamide Ifosfamide | Hemorrhagic cystitis (bladder bleeding) |
| Cisplatin | Highly emetogenic drug |
| Busulfan | Pulmonary fibrosis (‘busulfan lung’) |
| Methotrexate | Ulcerative stomatitis, pulmonary toxicity |
| Docetaxel | Edema |
Anthracycline Drugs
| Cardiotoxicity |
| Thalidomide | Phocomelia |
| Carmustine | Pulmonary toxicity (high doses) |
| Vincristine | Ascending paralysis / death when administered via the intrathecal route |
| Capecitabine | ‘Hand-foot syndrome’ Redness, pain, swelling and sometimes blisters on palms of hands / soles of feet. |
| Bortezomib | Increased risk of shingles |
| Tamoxifen | Increased risk of endometrial cancer |
| Nilotinib | Black-box warning for QT prolongation |
| Bleomycin | Pneumonitis |
| Bevacizumab | Bleeding / nosebleeds, proteinuria |
With these side effects in mind, let’s now review the pharmacology of anticancer drugs as it relates to mechanisms of action and drug indications.
Anticancer Drugs Pharmacology
| Drug Class | Examples | Mechanism / Notes |
|---|---|---|
| Alkylating agents | Cyclophosphamide Ifosfamide Carmustine Lomustine Bendamustine Busulfan Chlorambucil Streptozotocin Procarbazine | These drugs attache an alkyl group (CnH2n+1) to DNA. The alkyl group is attached to the guanine base of DNA, at the number 7 nitrogen atom of the purine ring. Carmustine / lomustine / streptozotocin are classified as nitrosoureas. Streptozotocin is used to treat metastatic cancer of pancreatic islet cells. Procarbazine is a nonclassical drug. |
| Alkylating-like | Cisplatin Carboplatin Oxaliplatin | Act in a similar manner to alkylating agents, but do not have an alkyl group. They damage DNA by interfering in the DNA repair process. Cisplatin remains one of the most emetogenic chemotherapy drugs. |
| Antimetabolites | 5-fluorouracil 6-mercaptopurine Capecitabine Gemcitabine Cytarabine Cladribine Floxuridine Hydroxycarbamide Methotrexate Pemetrexed Pentostatin | These drugs resemble nucleotides/bases of DNA or RNA – blocking enzymes needed for DNA synthesis or being incorporated into DNA or RNA; interfering in replication or causing apoptosis. Purines – guanine, adenine Pyrimidines – cytosine, thymidine, uracil Capecitabine is a prodrug of 5-fluorouracil. Methotrexate / pemetrexed are antifolates, inhibiting dihydrofolate reductase (DHFR). |
| Antimicrotubule drugs | Vinca alkaloids Vincristine Vinblastine Vinorelbine Taxanes Paclitaxel Docetaxel | Plant-derived drugs that prevent microtubule function – alpha and beta-tubulin are needed for cell division. Vinca alkaloids prevent microtubule formation, whereas taxanes prevent microtubule disassembly. Vinca alkaloids derive from the Madagascar Periwinkle, whereas taxanes derive from the Pacific Yew tree. |
| Topoisomerase inhibitors | Topoisomerase I Irinotecan Topotecan Topoisomerase II Etoposide Doxorubicin Daunorubicin Mitoxantrone Teniposide | Topoisomerase enzymes are needed for the normal unwinding of DNA to occur during replication or transcription. Topoisomerase I inhibitors are derived from camptothecin – taken from the Chinese ornamental tree, Camptotheca acuminata. Irinotecan is associated with severe diarrhea. |
| Cytotoxic antibiotics | Anthracyclines Epirubicin Idarubicin Doxorubicin Daunorubicin Bleomycins Bleomycin Mitomycin C | Anthracyclines impact topoisomerase II (above)but are also classified as anthracyclines that cause DNA intercalation and generating reactive oxygen species. Bleomycin produces free radicals that damage DNA. Mitomycin C can alkylate DNA. |
| Monoclonal antibodies | Alemtuzumab Bevacizumab Cetuximab Ipilimumab Ofatumumab Rituximab Trastuzumab | CLL; CTCL; T-cell lymphoma Kidney, colon, rectum, cervix, brain Colon, rectum; head and neck Melanoma Chronic lymphocytic leukemia Non-Hodgkin’s lymphoma; CLL HER2-receptor positive breast cancer |
| Proteasome inhibitors | Bortezomib Carfilzomib Ixazomib | Proteasome inhibitors are all used to treat multiple myeloma. Bortezomib is also used to treat mantle cell lymphoma. Proteasome inhibitors – bortezomib and ixazomib – work by reversibly inhibiting the protein proteasome subunit, beta type-5 (PSMB5). In contrast, carfilzomib irreversibly blocks the protein. |
| Tyrosine kinase inhibitor | 1st Generation Imatinib 2nd Generation Nilotinib Bosutinib Dasatinib Ponatinib | Imatinib is used to treat CML; ALL; GI stomal tumors and a variety of other cancers. Imatinib works by stopping the Bcl-Abl tyrosine kinase – slowing cancer growth or causing apoptosis. Nilotinib is used to treat imatinib-resistant chronic myelogenous leukemia (CML). Nilotinib is up to 10-30x more potent than imatinib. Bosutinib, dasatinib and ponatinib also used to treat ALL. All tyrosine kinase drugs are all taken orally. |
| Hormone-based Drugs | Tamoxifen Anastrozole Bicalutamide Leuprorelin | Tamoxifen is used to prevent / treat breast cancer.Tamoxifen works as a selective estrogen receptor modulator that decreases the growth of breast cancer cells. Anastrozole is a hormone receptor positive breast cancer. It works as an aromatase inhibitor, blocking the creation of estrogen. Bicalutamide is used to treat prostate cancer. Bicalutamide is a non-steroidal anti-androgen that blocks the androgen receptor (AR). Leuprorelin is a GnRH analog used to treat prostate and breast cancer. |
| Recombinant G-CSF | Filgrastim | Filgrastim is a recombinant form of naturally occurring granulocyte colony stimulating factor (G-CSF) – used to treat low blood neutrophils in patients following chemotherapy. |
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Anticancer drugs pharmacology doesn’t need to be difficult.
Once you understand the mechanism of action, that alone can go a long way. Above, for example, we saw how antimetabolites resemble nucleotides/bases and, by examining the names of each drug, you can draw a solid link.
Along with the above medicines, other immunosuppressant drugs may be used. For example, drugs such as azathioprine, cyclosporine, methylprednisolone, hydrocortisone and dexamethasone are routinely deployed as a part of the wider chemotherapy treatment plan.
One of the best ways to learn anticancer drugs pharmacology is to test yourself. That’s why we’ve put together a comprehensive range of anticancer drug NAPLEX practice questions for you to try.
That way, you eliminate the risk of performing badly on the day of your next pharmacy exam.
