anticancer drugs pharmacology

Anticancer Drugs Pharmacology

NAPLEX Study Guide

Pharmacology

June 5th, 2019by admin

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

  • Doxorubicin
  • Daunorubicin
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.

Don’t stop now! Prepare for the 2019 NAPLEX Exam!

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