Drug Classification: Infection

Aciclovir

UNDER REVIEW (September 2016)

Mechanism of Action:
A partial nucleoside analogue with the sugar ring replaced by an open-chain structure. Converted to aciclo-GTP (by thymidine kinase) which is a very potent inhibitor of viral DNA polymerase; it has approximately 100 times higher affinity to viral than cellular polymerase reducing toxicity towards human cells. Its monophosphate form also incorporates into the viral DNA, resulting in chain termination. It has also been shown that the viral enzymes cannot remove acyclo-GMP from the chain, which results in inhibition of further activity of DNA polymerase.

Lecture and CAL materials:

Dapsone

Indications:

  • Antimicrobial: Leprosy; prophylaxis of malaria, pneumocystis
  • Disease-modifying drug in cutaneous vasculitis and some other skin conditions.

Mechanism of Action:

Dapsone is an antibiotic most commonly used for the treatment of Mycobacterium leprae infections (leprosy). Dapsone can also be used to treat dermatitis herpetiformis and other skin conditions. Dapsone is thought to act by depleting the body’s stores of para-aminobenzoic acid (PABA).

Lecture and CAL materials: (under review)

Oseltamivir

UNDER REVIEW (September 2016)

Mechanism of Action:

Oseltamivir reduces replication of influenza A and B viruses by inhibiting viral neuraminidase.

 

Zidovudine

UNDER REVIEW (September 2016)

Mechanism of Action:

This nucleoside reverse transcriptase inhibitor (or ‘nucleoside analogue’) was the first anti-HIV drug to be introduced. Like other reverse transcriptase inhibitors, AZT works by inhibiting the action of reverse transcriptase, the enzyme that HIV uses to make a DNA copy of its RNA. Reverse transcription is necessary for production of the viral double-stranded DNA, which is subsequently integrated into the genetic material of the infected cell (where it is called a provirus). The azido group increases the lipophilic nature of AZT, allowing it to cross cell membranes easily by diffusion and thereby also to cross the blood-brain barrier. Cellular enzymes convert AZT into the effective 5′-triphosphate form. Studies have shown that the termination of the formed DNA chains is the specific factor in the inhibitory effect.

 

Rifampicin

Indications:

  • Treatment of Mycobacterial infections, including M. tuberculosis and M. leprae
  • Sometimes used as a conventional antibiotic, e.g. in post-exposure prophylaxis of contacts of patients with Meningococcal infection, and as part of therapy for some deep Staph. aureus (including MRSA) infections.

Mechanism of Action:

A rifamycin, a class of agents that interfere with microbial RNA production.

Lecture and CAL materials: (under review)

Isoniazid

Indications:

  • Treatment of Mycobacterial infections, in combination with other drugs
  • In some circumstances, prophylaxis against reactivation of TB

Mechanism of Action:

Isoniazid (isonicotinylhydrazide, INH) is an anti-mycobacterial drug that is particularly active against Mycobacterium tuberculosis. The mechanism of action is not known, but it is thought to work through its effects on lipids (fats) and DNA within the tuberculosis bacterium. It is very selective for mycobacteria, that is, it has few if any effects on other bacteria.

Lecture and CAL materials: (under review)