Series of Pharmacology lectures to undergraduate medical students, based on illustrations and hints that aid studying from standard textbook.

1. CHEMOTHERAPY
HIGHLIGHTS
MOHAMED BAHR; MD, PHD
Antiviral Drugs

2. Mohamed Bahr; MD, PhD
ANTIVIRAL
DRUGS

3. Mohamed Bahr; MD, PhD

4. Mohamed Bahr; MD, PhD
STEPS TARGETED BY
ANTIVIRAL DRUGS
1., 2., 3. Adsorption, penetration, and uncoating: viruses have no
metabolic machinery and have to enter host cell and use its metabolic
processes to replicate.
4. a. Early protein synthesis: synthesis of viral RNA and DNA
polymerases.
b. Synthesis of nucleic acids (RNA and DNA) and coat
proteins: by RNA and DNA polymerases in RNA and DNA viruses
respectively. In HIV, reverse transcriptase makes a DNA copy of viral
RNA.
Late structural protein synthesis by viral protease (in HIV) → viral
protein processing → mature virion core.

5. Mohamed Bahr; MD, PhD
5. Assembly of the formed nucleic acid and coat proteins into
new viral particles.
6. Release of new viral particles from host cell, facilitated by
neuraminidase.

6. Mohamed Bahr; MD, PhD
Drug Mechanism Disease
Antiherpesvirus
agents
Inhibits DNA
polymerase
A. Acyclovir Herpes: H simplex
- H zoster –
chickenpox
B. Ganciclovir CMV pneumonia
and retinitis
(immunocomprom
ised).
Idoxuridine

7. Mohamed Bahr; MD, PhD
Drug Mechanism Disease
Anti-influenza agents RNA virus
A. Amantadine Inhibits penetration and
uncoating
Influenza A -parkinsonism
B. Oseltamivir
C. Zanamivir
Inhibition of
neuraminidase →
inhibition of viral release
Influenza A (Avian)
Influenza B →
Prophylaxis – treatment.

8. Mohamed Bahr; MD, PhD
Antihepatitis agents Inhibits DNA
polymerase
A. Adefovir dipivoxil
B. Lamivudine
C. Interferon-α and
Peginterferon-α 2A, 2B
Other antiviral agents
Ribavirin Inhibits RNA polymerase
And mRNA synthesis
Hepatitis C (+ IFN)
Respiratory syncytial
Virus
Influenza A and B

9. Mohamed Bahr; MD, PhD
Retroviral
A. Nucleoside Reverse
Transcriptase Inhibitors
Zidovudine Inhibit reverse
transcriptase → inhibition
of replication
B. Non-nucleoside
Reverse Transcriptase
Inhibitors
Nevirapine
C. Protease Inhibitors
Indinavir
Ritonavir
Inhibits protease →
inhibition of viral protein
processing
Entry Inhibitors
Enfuvirtide

10. Mohamed Bahr; MD, PhD
IMMUNOGLOBULINS
(GAMMA-GLOBULIN)
• Pooled immunoglobulins (IgGs) containing antibodies
against virus envelope → inhibition of viral adsorption and
penetration.
• Used before symptoms (viremia) → attenuates or prevents
measles, infectious hepatitis, and poliomyelitis (passive
immunization, offers 3weeks protection).

11. Mohamed Bahr; MD, PhD
ADVERSE EFFECTS OF
ANTIVIRAL DRUGS
 Acyclovir: N and V, headache, confusion, seizures, renal stones, eye stinging.
 Ganciclovir: myelosupression - retinal detachment (with intraocular implants).
 Amantadine: insomnia – hallucination.
 Zanamivir/Oseltamivir: N and V – nose and throat irritation (inhaled
zanamivir).
 Ribavirin: Anemia - upper airway irritation (with aerosol) – teratogenic.
 Zidovudine: myelosupression -flu like syndrome - cholestatic hepatitis.
 Indinavir: N and V, enzyme inhibitor, renal stones, central adiposity
(cushinoid).

12. Mohamed Bahr; MD, PhD
Types
IFN-α and and IFN-β:
produced by B and T
lymphocytes, macrophages,
and fibroblasts, in response
to viruses and cytokines →
antiviral effect
IFN-γ: produced by T
lymphocytes in response to
viruses, rickettsiae, protozoa
→ immunostimulant effect
Pegylated IFN-α: higher
efficacy and longer acting
than IFN-α → SC once/wk

13. Mohamed Bahr; MD, PhD
MECHANISM
Bind to specific cell membrane receptors → inhibition of viral
penetration, translation, transcription, protein processing,
maturation and release.
↑ Phagocytic activity of macrophages.
↑ Proliferation of cytotoxic T cells.

14. Mohamed Bahr; MD, PhD
USES
Hepatitis B and C.
Herpes: Disseminated infections in cancer patients.
HIV infection (AIDs).
Hairy cell leukemia (cytotoxic)

15. Mohamed Bahr; MD, PhD
ADVERSE EFFECTS
1. Flu-like syndrome: fever, chills, myalgia and GIT upset.
2. CNS effects: dizziness - headache- confusion.
3. CVS effects: hypotension- arrhythmias.
4. Bone marrow depression.
5. Alopecia.

16. Mohamed Bahr; MD, PhD
TREATMENT OF CORONAVIRUS
- Traditionally, there were no effective antiviral
agents for coronaviruses.
- Initial efforts focused on the use of currently
available drugs, either conventional antiviral
agents or non-antivirals with inhibitory
effects.

17. Mohamed Bahr; MD, PhD
REFERENCES
Lippincott’s Illustrated Reviews, 5th ed.
Color Atlas of Pharmacology, 2nd ed.
Goodman and Gilman's The Pharmacological Basis of
Therapeutics, 12th ed.