Download Antifungal Drugs

Antifungal Drugs
 Inhibition of ergosterol synthesis
 Polyenes
 Amphotericin B
 Inhibition of cell wall synthesis
 Echinocandins
 Inhibit synthesis of -glucan
 Cancidas is used against Candida and Pneumocystis
 Azoles
 Miconazole
 Triazoles
 Allylamines
 For azole-resistant
infections
Inhibition of Nucleic Acids
 Flucytocine
 Cytosine analog interferes with RNA synthesis
 Pentamidine isethionate
 Anti-Pneumocystis; may bind DNA
Other Antifungal Drugs
 Griseofulvin
 Inhibits microtubule formation
 Superficial dermatophytes
 Tolnaftate
 Action unknown
Antiviral Drugs
 Nucleoside and nucleotide analogs
Nucleoside and Nucleotide Analogs
Antiviral Drugs
 Protease inhibitors
 Indinavir: HIV
 Integrase inhibitors
 HIV
 Inhibit attachment
 Zanamivir: Influenza
 Block CCR5: HIV
 Inhibit uncoating
 Amantadine: Influenza
Enzyme Inhibitors
 Fusion inhibitors
 Enfuvirtide: HIV
 Inhibit attachment
 Zanamivir: Influenza
 Inhibit uncoating
 Amantadine: Influenza
Interferons
 Prevent spread of viruses to new cells
 Alpha interferon: Viral hepatitis
 Imiquimod
 Promotes interferon production
Antiprotozoan Drugs
 Chloroquine
 Inhibits DNA synthesis

Malaria
 Diiodohydroxyquin
 Unknown mode of action

Amoebic diseases
Antiprotozoan Drugs
 Metronidazole
 Damages DNA
–
Entamoeba, Trichomonas
 Nitazoxanide
 Interferes with metabolism of anaerobes
Antihelminthic Drugs
 Niclosamide
 Prevents ATP
generation

Tapeworms
 Praziquantel
 Alters membrane
permeability

Flatworms
Antihelminthic Drugs
 Mebendazole
 Inhibits nutrient
absorption

Intestinal roundworms
 Ivermectin
 Paralyzes worm

Intestinal roundworms
Resistance to Antibiotics
Antibiotic Resistance
 A variety of mutations can lead to antibiotic resistance
 Mechanisms of antibiotic resistance
1. Enzymatic destruction of drug
2. Prevention of penetration of drug
3. Alteration of drug's target site
4. Rapid ejection of the drug
 Resistance genes are often on plasmids or transposons that can be
transferred between bacteria
 Misuse of antibiotics selects for resistance mutants. Misuse includes
 Using outdated or weakened antibiotics
 Using antibiotics for the common cold and other inappropriate
conditions
 Using antibiotics in animal feed
 Failing complete the prescribed regimen
 Using someone else's leftover prescription
Effects of Combinations of Drugs
 Synergism occurs when the effect of two drugs
together is greater than the effect of either alone
 Antagonism occurs when the effect of two drugs
together is less than the effect of either alone
Future of Chemotherapeutic
Agents
 Antimicrobial peptides
 Broad-spectrum antibiotics



Nisin (lactic acid bacteria)
Magainin (frogs)
Cecropin (moths)
 Antisense agents
 Complementary DNA that binds to a pathogen's
virulence gene(s) and prevents transcription
 Fomivirsen to treat CMV retinitis
Future of Chemotherapeutic
Agents
 siRNA
 Complementary RNA
that binds mRNA to
inhibit translation
Assignment (test 3)
 Explain why antiviral drugs are very difficult to develop. What
are the possible targets that can be exploited in developing an
antiviral drug?
 In some cases, resistance to an antibiotic can spread very quickly
through a microbial population. How does this happen?
 Explain how β-lactam antibiotics kill bacteria. Why does
penicillin kill only Gram positive bacteria that are actively
growing?
 Many pathogens have become resistant to antibiotics. What are
the mechanisms of antibiotic resistance?