Description of Antimalarial Drugs – PST04211 Basic Pharmacology
NTA Level 4 • Semester 2 • PST04211 Description of Antimalarial Drugs Basic Pharmacology • Source Session/Topic 10 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 10: Description of Antimalarial Drugs Total Session Time: 120 minutes + 2 hours Assignment Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • List indications of antimalarial drugs • List contraindications of antimalarial drugs • Describe dose, dosage and course of antimalarial drugs • List side effects and adverse effects of antimalarial drugs • Describe interactions and precautions of antimalarial drugs Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board and chalk/whiteboard markers • Overhead projector and computer 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 PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide 55 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 • What are indications of antimalarial drugs? 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 • The indications of antimalarial drugs depends on the stage of disease and are classified as 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 • The indications of different antimalaria drugs: 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 PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide 56 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 • Chloroquine is contraindicated in patients with 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. PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide 57 • Quinine (or quinidine) 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 • Artemisinins 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) • Artemether & Lumefantrine 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