QuestionSBA
QuestionChoice
Methotrexate is a competitive inhibitor of the dihydrofolate reductase enzyme, which is involved with catalyzing dihydrofolate to the active tetrahydrofolate. 



This is needed for the synthesis of the nucleoside thymidine, and is part of the synthesis of purine and pyrimidine. In essence, methotrexate inhibits the synthesis of DNA and RNA
1316
a
Methotrexate
QuestionChoice
Vinblastine is a vinka alkaloid, which works by affecting the microtubule assembly, and subsequently the spindle formation
1320
e
Vinblastine
QuestionChoice
This option is incorrect as it is not a folate antagonist, but rather an alkylating agent. Alkylating agents work by adding an alkyl group to some of the proteins of the double helix structure of a DNA molecule. This prevents the linking up of the proteins, causing breakage of the DNA strands (the lack of which causes death of the cancer cell)
1317
b
Cisplatin
QuestionChoice
This option is incorrect as it is not a folate antagonist, but rather an alkylating agent. Alkylating agents work by adding an alkyl group to some of the proteins of the double helix structure of a DNA molecule. This prevents the linking up of the proteins, causing breakage of the DNA strands (the lack of which causes death of the cancer cell)
1318
c
Cyclophosphamide
QuestionChoice
Bleomycin works by inducing DNA strand breaks. It is often used in combination with doxorubicin in Hodgkin’s lymphoma as they have additive and complementary effects on the DNA (doxorubicin acts by intercalating between DNA strands)
1319
d
Bleomycin
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hey guys :P
50233
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Concept
Chapter
#### Monitoring

The BNF advises to monitor lung function (in patients with a history of obstructive airway disease).

#### Overdoses

Overdosages with beta-blockers may cause cardiac effects such as bradycardia, hypotension, syncope, conduction abnormalities, and heart failure. Bradycardia is the most common arrhythmia, but some beta-blockers may induce ventricular tachyarrhythmias secondary to prolongation of QT interval (e.g. sotalol) or QRS duration (e.g. propranolol).
Non-cardiovascular effects include central nervous system effects (including drowsiness, confusion, convulsions, hallucinations, and in severe cases coma), respiratory depression, and bronchospasm.

Management
 - Airway protection 
 - Activated charcoal within 1 hour
 - IV Fluids
 
IV glucagon is the first-line management.
 
For symptomatic bradycardia, IV atropine may be used.

2618
2837
Lithium monitoring
Topic
89
Psychiatric Pharmacology
264
Which of the following drugs is a folate antagonist?
a