Description of Antimalarial Drugs

Session 10: Description of Antimalarial Drugs

Total Session Time: 120 minutes + 2 hours Assignment

Prerequisites

Learning Tasks

By the end of this session students are expected to be able to:

Resources Needed:

SESSION OVERVIEW

Activity/

Step Time Content

Method

1 05 minutes Presentation Introduction, Learning tasks

Presentation/

2 20 minutes Indications of Antimalarial Drugs

Buzzing

Presentation/

3 20 minutes Contraindications of Antimalarial Drugs

Brainstorming

Dose, Dosage and Course of Antimalarial

4 20 minutes Presentation

Drugs

Presentation/ Side Effects and Adverse Effects of

5 20 minutes

Brainstorming Antimalarial drugs

Interactions and Precautions of Antimalarial

6 15 minutes Presentation

Drugs

7 05 minutes presentation Key points

8 05 minutes presentation evaluation

9 10 minutes Presentation Assignment

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SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing.

STEP 2: Indications of Antimalarial Drugs (20minutes)

Activity: Buzzing (5 minutes)

ASK students to pair up and buzz on the following question for 2 minutes

ALLOW few pairs to respond and let other pairs to add on points not mentioned

WRITE their response on the flip chart/board

CLARIFY and SUMMARIZE by using the content below

follows:

o Drugs that eliminate developing or dormant liver forms of malaria parasite are called

tissue schizonticides

o Those that act on erythrocytes stage of malarial parasites are blood schizonticides

o Those that kill sexual stages of malaria parasites and prevent transmission to

mosquitoes are gametocides

o No one available agent can reliably affect a radical cure, that is, eliminate both hepatic

and erythrocytic stages of malaria parasite

o Few available agents are causal prophylactic drugs, that is, capable of preventing

erythrocytic malaria infection

o However, all effective malaria chemoprophylactic agents kill erythrocytic parasites

before they increase sufficiently in number to cause clinical disease

o Chloroquine

 Is a highly effective blood schizonticide

 It is also moderately effective against gametocytes of P. vivax, P. ovale, and P.

malariae but not against those of p falciparum

 Chloroquine is not active against liver stage parasites

 But its utility against p falciparum has been seriously compromised by drug

resistance

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o Amodiaquine

 Amodiaquine is closely related to chloroquine, and it probably shares mechanisms

of action and resistance with that drug

o Quinine & Quinidine

 Quinine is a rapidly acting, highly effective blood schizonticide against the four

species of human malaria parasites

 The drug is gametocidal against P. vivax and P. ovale but not P. falciparum

 It is not active against liver stage parasites.

 The mechanism of action of quinine is unknown

o Artemisinin and its derivatives

 Are very rapidly acting blood schizonticides against all human malaria parasites

 Artemisinins have no effect on hepatic stages of malaria parasites

 Artemisininsin particular artesunate and artemether are playing an increasingly

important role in the treatment of multidrug-resistant p falciparum malaria

 They are the only drugs reliably effective against quinine resistant strains

The most important of these analogs are:

 Artesunate (water-soluble; useful for oral, intravenous, intramuscular, and rectal

administration)

 Artemether (lipid-soluble; useful for oral, intramuscular, and rectal

administration)

o Lumefantrine

 Is an aryl alcohol related to halofantrine, is available as a fixed-dose combination

with artemether as Coartem in some countries

 Coartem is highly effective in the treatment of falciparum malaria

STEP 3: Contraindications of Antimalarial Drugs (20 Minutes)

Activity: Brainstorming (5 minutes)

Ask students to brainstorm on the following question:

What are contraindications of antimalarial drugs?

ALLOW few students to respond

WRITE their responses on the flip chart/ board

CLARIFY and SUMMARISE by using the content below

o Psoriasis or porphyria, in whom it may precipitate acute attacks of these diseases

o It should generally not be used in those with retinal or visual field abnormalities or

myopathy.

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o Should be discontinued if signs of severe cinchonism, hemolysis, or hypersensitivity

occur

o It should be avoided if possible in patients with underlying visual or auditory

problems

o It is contraindicated the first trimester of pregnancy if possible because teratogenicity

has been seen in animal studies, but limited inadvertent use in pregnancy has

apparently not led to fatal problems

o Is avoided in breast feeding mother whose infant is below 5kg body weight

STEP 4: Dose, Dosage and Course of Antimalarial Drugs (30 minutes)

o Dosage of Artemether 20mg & Lumefantrine 120mg tablets according to weight and

age

WT(Kg) AGE Day 1 Day1 Day2 Day2 Day 3 Day3

O hr 8hrs 24 hrs 36 hrs 48hrs 60hrs

5-14 3mon-3yrs 1 1 1 1 1 1

15-24 3yrs-8yrs 2 2 2 2 2 2

25-34 8yrs-12yrs 3 3 3 3 3 3

35 12yrs 4 4 4 4 4 4

above above

o The first dose should be given as Direct Observed Therapy(DOT)

o The second dose should strictly be given after 8hours

o Subsequent doses could be given twice daily (morning-evening) until completion of 6

doses

o Oral dose

o Intravascular route

 Quinine should be diluted four times in water for injection to a concentration of 60

o Intravenous route

5% dextrose or dextrose-saline and infused over 4 hours and repeated every 8

hours

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STEP 5: Side Effects and Adverse Effects of Antimalarial Drugs

(20 minutes)

Activity: Brainstorming (5 minutes)

Ask students to brainstorm on the following question:

ALLOW few students to respond

WRITE their responses on the flip chart/ board

CLARIFY and SUMMARISE by using the content below

o Adverse effects and side effects

 Therapeutic dosages of quinine and quinidine commonly cause tinnitus, headache,

nausea, dizziness, flushing, visual disturbances and a constellation of symptoms

termed cinchonism

 Mild symptoms of cinchonism do not warrant the discontinuation of therapy

 More severe findings, often after prolonged therapy, include more marked visual

and auditory abnormalities, vomiting, diarrhoea, and abdominal pain

 Hypersensitivity reactions include skin rashes, urticaria, angioedema, and

bronchospasm

 Therapeutic doses may cause hypoglycaemia through stimulation of insulin

release; this is a particular problem in severe infections and in pregnant patients,

who have increased sensitivity to insulin

 Quinine can stimulate uterine contractions, especially in the third trimester

 However, this effect is mild, and quinine and quinidine remain the drugs of choice

for severe falciparum malaria even during pregnancy

 Intravenous infusions of the drugs may cause thrombophlebitis

o Adverse effects and side effects

 Pruritus is common, Nausea, vomiting, abdominal pain, headache, anorexia,

malaise, blurring of vision, and urticaria are uncommon

 Large intramuscular injections or rapid intravenous infusions of chloroquine

hydrochloride can result in severe hypotension and respiratory and cardiac arrest

o Adverse effects and side effects

 The most commonly reported adverse effects have been nausea, vomiting, and

diarrhea

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 Irreversible neurotoxicity has been seen in animals, but only after doses much

higher than those used to treat malaria

STEP 6: Interactions and Precautions of antimalarial drugs (15minutes)

o Interact with the following group of drugs

 Amiodarone

 Quinolone

 Antidepressants

 Imidazoles

 Antipsychotics

 Antivirals

 β-blockers

 Cimetidine

o Interact with the following drugs

 Should not be given concurrently with mefloquine

 Should be used with caution in a patient with malaria who has previously received

mefloquine chemoprophylaxis

 Absorption may be blocked by aluminium-containing antacids

 Quinine can raise plasma levels of warfarin and digoxin

 Do not give concurrent with anti psychotics

o Precaution

 Severe hypotension can follow too-rapid intravenous infusions of quinine or

Quinidine

 It must be used with great caution in those with underlying cardiac abnormalities

 Dosage must be reduced in renal insufficiency

o Interaction

 The antidiarrheal agent kaolin and calcium- and magnesium-containing antacids

interfere with the absorption of chloroquine and should not be co administered

with the drug

o Precaution

 Chloroquine should be used with caution in patients with a history of liver disease

or neurologic or hematologic disorders

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Step 7: Key Points (5 minutes)

plus piperaquine (DPQ) and chloroquine

of the disease

STEP 8: Evaluation (5minutes)

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References

Robert, L. Talbert, Gary C. Yee, Gary R. Matzke, Barbara G. Wells, L. Michael.

2014. Pharmacotherapy: a pathophysiologic approach (9th ed.). New York,

McGraw-Hill Education.

Ministry Of Health and Social Welfare. 2013. Standard Treatment Guidelines &

National Essential Medicines List Tanzania Mainland (4th ed.).Dar es

salaam, Tanzania government printers.

Sally, S.R, Jeanne C.S. 2000. Introductory Clinical Pharmacology (6th ed) New York,

Lippincott Williams and Wilkins

School of Pharmaceutical sciences. 2011. Tanzania Pharmaceutical Handbook

(2nd ed.). Dar es Salaam, ARDHI University press.

The Royal Pharmaceutical Society of Great Britain. 2007. Martindale, the Extra

Pharmacopoeia (5TH ed). London, pharmaceutical press.

The Royal Pharmaceutical Society of Great Britain. 2009. British National Formulary

(59th ed). London, BMJ Group and RPS Publishing.

PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide

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