Pharmacology of Anti-cancer drugs Flashcards
At the end of the sessions, you will be able
to
• Identify the mechanism of action of major
classes of chemotherapy and targeted
agents
• Describe the common adverse effects of
these agents
• Discuss the strategies to prevent and/or
manage common toxicities of these agents
1
Anti-cancer drug are dosed based on _________ as it correlates better from animals models when doing inter-specie comparisons, which affects ________ and __________.
- body surface area (mg/m2)
- cardiac output
- renal clearance
The 8 main classes of chemotherapy agents include:
- _______ agents
- _______ inhibitors
- Anti-_______
- Anti-_______
- _______ therapies
- _______ therapies
- I_________
- Miscellaneous
- Alkylating
- Enzyme
- metabolites
- microtubules
- Endocrine
- Targeted
- Immunotherapies
Cell cycle specific agents preferentially kill what type of cells?
Cell cycle non specific agents kill both normal and malignant cells to what kind of extent?
- Cell cycle specific agents preferentially kill PROLIFERATING cells
- Cell cycle non specific agents kill both normal and malignant cells to the SAME extent (i.e. radiation)
For both cell cycle specific/ non-specific agents, _______ cells are more favored.
proliferating
For cell cycle specific agents, toxicity is the greatest during which phase?
What type of infusion administration improves cytotoxicity against cancer cells?
cell cycle specific agents: exert their toxic effect on proportion of cells in the part of the cell cycle in which the agent is active
- toxicity is the greatest during S phase of DNA synthesis
- Administering as CONTINUOUS INFUSION allows more exposure to more cells in the specific cycle
Which phases do Cell Cycle Non-Specific Agents Exert their cytotoxic effect?
Their cell kill is proportional to ____.
- Cell Cycle Non-Specific Agents Exert their cytotoxic effect THROUGHOUT the cell cycle, including the resting phase
- Their cell kill is proportional to DOSE
Cell Cycle Non-Specific Agents Agents include _________ agents, ___ antibiotics, antitumor antibiotics, ___ , altretamine.
- alkylating
- anthracycline
- nitrosoureas
Chemo drugs can cause acute toxicity by ___. Tissues with ___ i.e. bone marrow, GI mucosal cells, skin/hair are most affected, frequently leading to bone marrow suppression, mucositis, aloepecia and anaemia.
- inhibiting host cell division
- fast renewal cell populations
Cells that are rapidly dividing are most susceptible to acute toxicities
Chemo drugs can cause delayed toxicity such as __ and ___.
- infertility
- secondary malignancies
(may be irreversible)
delayed toxicity: months to years after treatment
We should note the following delayed toxicities: ____-specific toxicity
___-induced cardiac toxicity and
Methotrexate-induced ___.
these are drug-specific toxicity
- Anthracycline
- pneumonitis (lung toxicity)
Alkylating agents include the following 6 classes:
- Alkyl ___
- Aziridines
- Hydrazine and Triazenes
- __ mustards
- N__
- __ analogues
- sulfonates
- Nitrogen
- Nitrosoureas
- Platinum
Alkylating agents work by generating an _____ which binds to _____ sites (-NH, -OH, -PO4, -SH groups), resulting in cross-linking and alkylation of DNA.
The _____ atom of guanine is highly susceptible to alkylation, and accounts for 90% of the alkylated sites in DNA
- positively charged carbonium ion (electrophilic carbocation)
- electron-rich nucleophilic sites
- N7
Alkylating agents can cause cytotoxic effect by:
- Inhibiting DNA __
- __ of DNA
- Strand __
- replication and transcription
- Mispairing
- breakage
Alkylators generally do not show __.
cross resistance
Generally, In general, the dose limiting toxicity (DLT) for alkylating agents is __
myelosuppression
Alkylating agents usually cause neutropenia with a nadir at __ days and recovery in __ days,
except for the __ class, which demonstrate delayed nadir and recovery.
- 6 to 10
- 14 to 21
- nitrosourea
Common toxicities for most alkylating agents include __(1)___, ____(2)____, __(3)_ and __(4)__ .
- mucositis
- chemotherapy induced nausea & vomiting (CINV)
- neurotoxicity
- alopecia
Long term toxicities for alkylating agents can include pulmonary ______, ____ and secondary __ (peak incidence approximately 4 years after treatment)
- fibrosis
- infertility
- leukemias
Cyclophosphamide is a __ that is __ in the liver.
- prodrug
2. activated
Cyclophosphamide is metabolized to __ (therapeutic cytotoxic effect) and __ (harmful cytotoxic effect).
- phosphoramide mustard (4-hydroxycyclophosphamide)
2. Acrolein
Acrolein is an impt metabolite of Cyclophosphamide as it can cause __ (more damaging on bladder than anywhere else). We need to give __ (mesna) to counteract this effect.
The effect of acrolein more pronounced in __.
- hemorrhagic cystitis
- radical scavengers
- ifosfamide
What dosage forms is Cyclophosphamide available?
What is the oral absorption % of Cyclophosphamide?
Should it be taken on empty stomach or taken with food?
50mg in sugar/film coated tablets and injection ROAs
> 75%
preferably taken w food to dec GI upset
How is Cyclophosphamide metabolised and excreted?
Metabolism mainly by microsomal enzymes in liver, cytochrome P450 (CYP) primarily CYP2B6
Excretion is primarily by enzymatic oxidation to active and inactive metabolites, which are mainly excreted by urine
Typical Cyclophosphamide doses (600-750 mg/m^2 ) are used for treatment of _(1)__ and __(2)__ cancer.
High doses (2 g/m^2 ) are used in (3).
- lymphomas
- breast
- bone marrow transplants
Toxicities of Cyclophosphamide include (1) (dose related), SIADH and (2) (rare, mostly when high doses are given/long term therapy). (3) may occur in high doses as well.
SE of __(4)__ and __(5)___ potential (>1g high moderate, <1g low moderate)
- Nausea and vomiting
- hemorrhagic cystitis
- Cardiac dysfunction
- myelosuppression
- emetogenic potential (substance that causes vomiting)
One way to counsel patient to reduce hemorrhagic cystitis is to __ and use the __.
- drink plenty of water
2. washroom frequently
Ifosfamide is an analogue of cyclophosphamide
that is activated in liver by __. It causes worse __ than Cyclophosphamide.
- CYP3A4
2. hemorrhagic cystitis
Ifosfamide is primarily excreted via the __ route.
renal
__ must be administered with ifosfamide, along with vigorous _______ with ______ liters of NS (saline) pre- and post-hydration.
- Mesna
- hydration
- 1.5-2
We should encourage patients on ifosfamide to increase __ and __.
- oral fluid intake
2. frequent voiding of urine as much as possible
Ifosfamide can cause Nausea and Vomiting, __Toxicity, __ and is Dose limited by __.
- CNS
- Nephrotoxicity
- hemorrhagic cystitis
Platinum analogues are alkylating like agents which form a ____.
1st gen example: __
2nd gen example: __
3rd gen example: __
- reactive electrophile that covalently binds to DNA
- Cisplatin
- Carboplatin
- Oxaliplatin
Cisplatin is indicated for a wide range of __. The dose limiting toxicity for Cisplatin is __.
- solid tumors
- acute and delayed CINV (cisplatin is the most emetic drug = alot of vomitting; thus strong anti-emetic drugs are given along with cisplatin)
It is recommended to verify any dose of Cisplatin exceeding ___ and its use is not recommended if SCr < __ mg/dL.
- 100mg/m^2/cycle
2. 1.5 (mild CKD)
Vigorous hydration with adequate urine flow rate is required for administration of __.
Prehydration and post hydration with KCl & Mg SO4 are required due to __.
- Cisplatin
2. electrolyte wasting effects
Cisplatin nephrotoxicity is characterized by deterioration of renal function and __. We can prevent this by:
• Hydration w/ at least 1-2 L IV __ pre- and concurrent with cisplatin, with __ supplementation
• Maintain urine output >__ ml/h
• Provide ___ and/or ___
• Prolong __
• Give the patient __
• Avoid in patient with ___ dysfunction: do not use if CrCl less than ___ml/min
- electrolyte wasting
- Normal saline
- K & Mg
- 100
- mannitol (hydration protocol)
- furosemide (loop diuretic)
- infusion time ( e.g. 24 hour infusion)
- Amifostine
- renal
- 30
An alternative for cisplatin use in patients with renal dysfunction is __.
carboplatin
Amifostine is a radical scavenger that may __ efficacy of Cisplatin. It is __, can be __ and is less commonly used than switching to carboplatin.
- reduce
- expensive
- myelosuppressive
Cisplatin may cause (1) (may be reversible) with 50% frequency after a cumulative dose of (2) mg/m^2.
Solution:
- The strategy of __(3)_____ dose/ __(4)___ to carboplatin may reduce both efficacy and side effects. Symptomatic relief is an option as well.
- Limit ___(5)___ doses
Medications to reduce __(6)____ pain: _(7)___, ____, ____
Cisplastin can be an _(8)____ to veins
- peripheral neuropathy
- 300-500
- reducing dose
- Substituting to carboplatin
- cumulative
- neuropathic
- gabapentin, amitriptyline, pyridoxine
- irritant
Cisplatin may cause __ (may be irreversible), which is related to __ peak doses. Patients often complain of being unable to __.
- ototoxicity
- high
- to hear high pitch sounds
___ employs a unique dosing based on the Calvert equation, where Dose = AUC X (GFR + 25). (AUC = 2 for wkly dosing, AUC = 5/6 for 3 wkly).
(Dose based on target area under curve, BSA not usually used)
Carboplatin
Carboplatin has a much lower incidence of __ , ototoxicity and ___ compared to to cisplatin. However, carboplatin can cause __ reactions.
- nephrotoxicity
- delayed Nausea and vomiting
- hypersensitivity
Carboplatin is indicated for a wide range of solid tumors (esp _____) but is dose limited by __ (especially __).
- ovarian
- myelosuppression
- Thrombocytopenia
__ is stable in D5W only (NOT saline). It is indicated for the treatment of __.
- Oxaliplatin
2. colorectal cancer
Oxaliplatin causes reversible ___ (often exacerbated by cold air). Compared to cisplatin, oxaliplatin shows much less __. Other toxicities include myelosuppression (much less than cisplatin) and __.
- cumulative peripheral neuropathy
- nephrotoxicity
- hypersensitivity
Enzyme inhibitors used in chemotherapy include Topoisomerase I inhibitors i.e. Irinotecan (Camptosar) that work by __ and Topoisomerase II inhibitors i.e. anthracyclines such as doxorubicin (Adriamycin) that work by __.
- cleavage of single strand DNA
2. Form a complex and cause double strand DNA breaks
Irinotecan (CPT-11) and its (even more) active metabolite SN-38 both bind to the Topoisomerase I-DNA complex, preventing __ , which ultimately leads to DNA breakage and death. It is cell cycle __ specific.
- re-ligation
2. S-phase
Irinotecan is indicated for the treatment of __ and is excreted via __.
- metastatic colorectal cancer
2. bile and urine
Irinotecan is dose limited by __ (both early: within 1st 24h and late: >24h) which can be managed using high doses of loperamide until the patient is __.
- Diarrhoea
- diarrhoea free for 12h
4mg at earliest sign of diarrhoea, followed by 2mg PO q2h until diarrhoea free for 12h
Cholinergic syndrome can occur with use of __, characterized by SLUD, which stands for __. We can prevent this with 0.25-1mg SC/IV __.
- Irinotecan
- Salivation/Sweating, Lacrimation, Urination, Diarrhoea
- Atropine
UGT1A1 undergoes conjugation reactions with __.
For patients with UGT1A1 deficiency demonstrate exceptional toxicity with use of __. A reduction of starting dose by at least 1 dose level if UGT1A1*28 homozygosity is detected.
- SN-38
- Irinotecan
1 dose level: 25% decrease
Etoposide is indicated for a wide range of __ and is available as __ or __ ROA. The __ (ROA) dose is twice greater than __ (ROA) dose.
- solid tumors
- PO (caplet)
- IV (injection)
- PO
- IV
Etoposide is dose limited by __ and __ (when infusions are given too quickly).
- Myelosuppression (primarily neutropenia)
2. Hypotension
Etoposide IV infusions should be given over a minimal duration of 1hr (usually 2hr) to avoid __ and the concentration should not exceed 0.4 mg/ml to avoid __. Use of non-PVC tubing is encouraged due to __.
- hypotension
- precipitation of infusion
- the use of polysorbates as diluents