Malaria Flashcards
1
Q
Qunine
Common indications
A
- Commonly used for treatment and prevention of night-time leg cramps. But should really be reserved for cases when cramps regulalry disrupt sleep and non-pharmacological methods, such as passive stretching exercises, have failed
- Quinine is a first-line treatment option for plasmodium falciparum malaria
2
Q
Quinine
MOA
A
- Leg cramps are caused by sudden, painful involuntary contraction of skeletal muscle
- Quinine is thought to act by reducing the excitability of the motor end plate in response to ACh stimulation
- This reduces the frequency of muscle contraction
- In malaria, the MOA of quinine is not well understood, but its overall effect leads to rapid killing of P.falciparum parasites in the schizont stage in the blood
3
Q
Quinine
Important adverse effects
A
- Although quinine is usually safe at recommended doses, it is potentially very toxic and can be fatal in overdose
- It can cause tinnitus, deadness and blindness (may be permenant), GI upset and hypersensitivity
- Qunine prolongs the QT interval and may therefore predispose to arrhythmias
- Hypoglycaemia can occur and can be particularly problematic in patients with malaria, which also predisposes to hypoglycaemia
4
Q
Quinine
Warnings
A
- Quinine should be prescribed with caution in people with existing hearing or visual loss
- It is teratogenic, so should not be prescribed in the first trimester of pregnancy, although in the case of malaria its benefits may outweigh this risk
- Qunine should be avoided in people with G6PD deficiency as it precipitates haemolysis
5
Q
Quinine
Interactions
A
- Any drug that increases QT interval (QT <400: Ondansetron, citalopram, antipsychotics, methadone, amiodarone, macrolides)
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6
Q
Quinine monitoring
A
- Leg cramps 200-300mg ON
- P.Falciparum- 600mg TDS
- For leg crams trial for 4 weeks, they are unlikely to experience any benefits and should stop taking it
7
Q
Chloroquine
Common indications
A
- Active rheumatod arthritis + Systemic and discoid lupus erythematosus- 155mg daily
- Prophylaxis of malaria- 300mg OW
- Treatment of non-falciparum malaria
- P.vivax OR Ovale infection during pregnancy while radical cure is postponed
8
Q
Chloroquine
MOA
A
- After passive diffusion, chloroquine becomes trapped in the acidic parasitic digestive vacuole in the protonated form
- Chloroquine caps hemozoin molecules to prevent further biocrystallization of haem => Haem build-up
- Chloroquine binds to haem to form a complex that is highly toxic to the cell and distrupts membrane function
- Toxic concentrations of haem and the complex => cell lysis => Parasite cell autodigestion
9
Q
Chloroquine
Adverse effects
A
- Allergic reactions
- Severe rash/blistering
- Cardomyopathy in long term high dosing
- Liver abnormalities- watch for signs of jaundice, dark urine, derranged LFTs
- Inflammation of the lungs
10
Q
Chloroquine
Warnings
A
- Diabetes- May lower BMs
- Cardiomyopathy- long term risk
- Neurological disorders- Myasthenia gravis
- Epilepsy- lowers seizure threshold
- Retinopathy- long term use
- Dosing equivalence and conversion between formulations- also watch for extremes of body weight- use IBW in obese pts
11
Q
Chloroquine
interactions
A
- Drugs known to prolong QT interval/ induce arrythmias- Metoclopramide, ondansetron, citalopran, Class IA and III anti-arrhythmics, amiodarone
- Ciclosporin- Increases exposure to ciclosporin
- Mefloquine- increase risk of convulsion
- Digoxin- increase exposure to digoxin
12
Q
Chloroquine
Monitoring
A
- For long term pt should have regular ophthalmological examination- Retinopathy
13
Q
Chloroquine
Patient advice
A
- Warn travellers going to malarious areas about importance of avoiding mosquito bites, importance of taking prophylaxis regularly, and importance of immediate visit to doctor if ill within 1 year and especially within 3 months of return
- For prophylaxis of malaria, must start 1 week before entering endemic area and continue for 4 weeks after leaving
14
Q
Mefloquine
Common indications
A
- Treatment of malaria
- Prophylaxis of malaria
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15
Q
Mefloquine
MOA
A
- Lariam acts on and destroys the asexual intraerythocytic forms of the human malaria parasites: Plasmodium falciparum, P. vivax. P. malariae and P. ovale. It is effective in the treatment and prophylaxis of malaria.
Lariam is also effective against malarial parasites resistant to other antimalarials such as chloroquine and other 4-aminoquinoline derivatives, proguanil, pyrimethamine and pyrimethamine-sulphonamide combinations.
