NTA Level 4 • Semester 2 • PST04211

Description of Antiviral Drugs

Basic Pharmacology • Source Session/Topic 15

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Session 15: Description of Antiviral Drugs

Total Session Time: 120 minutes

Prerequisites

None

Students Learning Tasks

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

• List indications of antiviral drugs

• List contraindication of antiviral drugs

• Describe dose, dosage and course of antiviral drugs

• List side effects and adverse effects of antiviral drugs

• Describe interaction and precaution of antiviral drugs

• Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

• Computer and LCD Projector

SESSION OVERVIEW

Activity/

Step Time Content

Method

1 05 minutes Presentation Introduction, Learning Objectives

15 minutes Indications, dosage, side effects,

Presentation

2 contraindications, interactions and precaution

Brainstorming

of acyclovir

15 minutes Indications, dosage, side effects,

3 Presentation contraindications, interactions and precaution

of gancyclovir

30 minutes

Indications, dosage, side effects,

Presentation

4 contraindications, interactions and precaution

Buzzing

of nucleoside reverse transcriptase inhibitors

30 minutes Presentation Indications, dosage, side effects,

contraindications, interactions and precaution

of non-nucleoside reverse transcriptase

inhibitors

15 minutes Presentation Indications, dosage, side effects,

6 Brainstorming contraindications, interactions and precaution

of protease inhibitors

7 05 minutes Presentation Key Points

8 05 minutes Presentation Evaluation

PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide

SESSION CONTENTS

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

READ or ASK students to read the learning objectives and clarify

ASK students if they have any questions before continuing.

STEP 2: Indications, Dosage, Side Effects, Contraindications, Interactions

Precaution of Acyclovir (15 minutes)

Activity: Brainstorming (5 minutes)

Ask students to brainstorm on the following question:

• What are indications of acyclovir?

ALLOW few students to respond?

WRITE their responses on the flip chart/ board

CLARIFY and SUMMARISE by using the content below

Antiviral drugs are a class of medication used for treating viral infections

Indications

Acyclovir is indicated to treat;

• Herpes simplex virus (hsv) infections

• Varicella-zoster virus (vzv) infections

Dose and Dosage

• Herpes Simplex

o Acyclovir (O) 400mg 8 hourly for 7 – 10 days

• Herpes Zoster (Shingles)

o Acyclovir cream 5% applied until vesicles desapear.

Plus

o Acyclovir (O) 800 mg 5 times a day until no new lesions appear

Side effects

• Nausea and vomiting,

• Abdominal Pain,

• Diarrhoea,

• Headache,

• Fatigue,

• Rash, urticaria and pruritus,

• Photosensitivity

PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide

Contraindications

Hypersensitivity to acyclovir or other related drugs

Interactions

Interactions do not apply to topical aciclovir preparations

• Ciclosporin: increased risk of nephrotoxicity when aci- clovir given with ciclosporin

• Probenecid: excretion of aciclovir reduced by pro- benecid (increased plasma

concentration)

Precautions

• Maintain adequate hydration

• In renal impairment

• In elderly

STEP 3: Indications, Dosage, Side Effects, Contraindications, Interactions

Precaution of Ganciclovir (15 minutes)

Indications

Ganciclovir is used to treat cytomegalovirus (cmv) infections

Dose and Dosage

By intravenous infusion,

Initially (induction) 5mg/kg every 12 hours for 14–21 days for treatment

Side effects

• Diarrhoea,

• Nausea, Vomiting,

• Dyspepsia,

• Abdominal Pain,

• Constipation,

• Flatulence,

• Dysphagia,

• Taste Disturbance,

• Leucopenia, Thrombocytopenia,

Contraindications

• Hypersensitivity to ganciclovir, aciclovir,

• Abnormally low haemoglobin, neutrophil, or platelet counts

Interactions

• Probenecid: excretion of ganciclovir reduced by probenecid

• Hence increased plasma concentration and risk of toxicity

Precautions

• Close monitoring of full blood count

• Ensure adequate hydration during intravenous administration

PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide

STEP 4: Indications, Dosage, Side Effects, Contraindications, Interactions

Precaution of Nucleoside Reverse Transcriptase Inhibitors (30

minutes)

Activity: Buzzing (5 minutes)

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

• What are commonly used nucleoside reverse transcriptase inhibitors?

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

Nucleoside Reverse Transcriptase Inhibitors (NRTIs) include:

• Zidovudine (AZT)

• Lamivudine (3TC)

• Abacavir (ABC)

• Emtricitabine (FTC)

• Stavudine (d4T)

• Tenofovir (TDF)

o Tenofovir is classified as Nucleotide Reverse Transcriptase Inhibitor

Indications

Nucleoside Reverse Transcriptase Inhibitors (NRTIs) are antiretroviral drugs that are

indicated for treatment of HIV/AIDS in combination with other antiretrovirals

Dose and Dosage

Zidovudine (AZT) 300 mg PLUS Lamivudine (3TC) 150 mg twice daily

OR

Tenofovir (TDF) 300mg PLUS Lamivudine (3TC) 150 mg twice daily

Side effects

• Gastrointestinal disturbances (nausea, vomiting, abdominal pain, diarrhoea)

• Lactic acidosis

• Lipodystrophy

• Anaemia by Zidovudine

• Hypersensitivity by Abacavir

• Peripheral neuropathy by Stavudine

• Nephrotoxicity by Tenofovir

PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide

Contraindications

• Zidovudine is contraindicated to patients with Anaemia

• Patients who are hypersensitive to the NRTIs

• Tenofovir is contraindicated to patients with renal failure

Interactions

Increased risk of haematological toxicity when Zidovudine given with NSAIDs

Precautions

• Monitor liver function when using NRTIs

• Monitor renal function when using Tenofovir

• Monitor red blood cell count when using Zidovudine

STEP 5: Indications, Dosage, Side Effects, Contraindications, Interactions

Precaution of Non-Nucleoside Reverse Transcriptase Inhibitors

(30 minutes)

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) include:

• Nevirapine (NVP)

• Efavirenz (EFV).

Indications

Non-nucleoside reverse transcriptase inhibitors are antiretroviral drugs used for the treatment

of HIV/AIDS in combination with other antiretrovirals

Dose

• Efavirenz (EFV) 600 mg once daily at night.

• Nevirapine (NVP) 200mg twice a day

Side effects

• Rashes due hypersensitivity reaction by Nevirapine

• CNS disturbances, abnormal dreams, hallucinations by Efavirenz

Contraindications

Efavirenz and Nevirapine are contraindicated in patients with acute porhyria

Interactions

Clarithromycin increase plasma levels of Efavirenz leading to increased risk of rash

Precautions

• Monitor liver function

• Close follow up when using Efavirenz inpatinets with history of mental illiness or

seizures

PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide

STEP 6: Indications, Dosage, Side Effects, Contraindications, Interactions

Precaution of Protease Inhibitors (15 minutes)

Activity: Brainstorming (5 minutes)

Ask students to brainstorm on the following question:

• What are commonly used protease inhibitors?

ALLOW few students to respond?

WRITE their responses on the flip chart/ board

CLARIFY and SUMMARISE by using the content below

Protease Inhibitors (PIs) include;

• Lopinavir (LPV)

• Atazanavir(ATV)

Indications

Protease Inhibitors (PIs) are antiretroviral drugs used to treat HIV/AIDS combination

with other antiretrovirals

Dose

• Lopinavir 800mg/Ritonavir 200mg

OR

• Atazanavir 300mg/Ritonavir 100mg.

Side effects

• Gastrointestinal disturbances (nausea, vomiting, abdominal pain, flatulence)

• Lipodystrophy syndrome (fat redistribution, insulin resistance and dyslipidaemia)

o Fat redistribution presents as loss of subcutaneous fat, increased abdominal

fat ‗buffalo hump‘ and breast enlargement

• Blood disorders (anaemia, neutropenia and thrombocytopenia)

Contraindications

PIs should not be given in patients with acute porphyria

Interactions

Ritonavir inhibit Lopinavir metabolism and increase plasma concentration of Lopinavir

Precautions

• Monitor blood sugar when PIs are used in Diabetic patients as they are associated

with hyperglycemia

• Monitor liver function

PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide

STEP 7: Key Points (5 minutes)

• Acyclovir is antiviral indicated for treatment of Herpes simplex virus (hsv) and

varicella-zoster infections

• The use of Ganciclovir is associated with blood abnormalities therefore close

monitoring of blood count is important

• Commonly used nucleoside reverse transcriptase include Zidovudine, Stavudine,

Lamivudine and Stavudine

• Efavirenz, a non-nucleoside reverse transcriptase inhibitors should be cautiously in

patients with history of mental illness and seizures

• Lopinavir is usually combined with another protease inhibitor Ritonavir, because it

increases plasma concentration of Lopinavir to therapeutic levels.

STEP 8: Evaluation (5 minutes)

• What are the indications of acyclovir?

• What are the side effects of ganciclovir?

• What are commonly used nucleoside reverse trancriptase inhibitors?

• What are the precautions for using non-nucleoside reverse trancriptase Efavirenz?

• What is the advantage of Lopinavir-Ritonavir drug interaction?

PST 04211 Basic Pharmacology NTA Level 4 Semester 2 Facilitator Guide

References

Talbert, R. L. Yee, G. C. Matzke, G. R. Wells, B. G. & Michael, L. (2014)

Pharmacotherapy: a pathophysiologic approach (9th ed.). New York: McGraw-Hill

Education.

MoHSW(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 (6thed) 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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