Influenza Treatment – Antiviral Drugs

00:00 Let's move on to a different category.

00:02 This is the category use to treat influenza.

00:06 Now anti influenza agents who work on several areas but the one that we talk about most is the decloaking of the influenza A virus.

00:17 Now amantadine is a prototypical drug and it blocks the uncoating of the virus.

00:23 It binds to a proton channel to prevent acidification of the virus core.

00:28 Now without acidification of the virus core you can't activate your RNA transcriptase.

00:34 So that viruses is essentially rendered inside the cell.

00:37 Now it doesn't effect the influenza B virus.

00:41 It tends to seem to only effect influenza A.

00:44 Note that amantadine is also an antiparkinsonian medication.

00:50 So we did talk about amantadine in our Parkinson's lecture.

00:54 Rimantadine does not require dosage adjustment in renal failure.

00:59 So it's a convenient agent as well that's part of the armaterium.

01:03 In terms of the toxicity of these two agents, mostly it involves GI irritation.

01:08 But sometimes you can get some strange neurological phenomenon too like slurred speech, dizziness and ataxia.

01:15 Is that due to the parkinsonian activity of the drug? We're not too sure.

01:20 The next agent I want to talk to you about in terms of influenza treatment is zanamivir.

01:25 These are neuraminidase inhibitors.

01:30 They act by cleaving sialic acid residues.

01:33 Now they prevent clumping of newly released virions.

01:37 So normally when viruses are being released or virions are being released, they clump together and we don't want that to happen.

01:46 Now these agents are inhibiting the neuraminidase.

01:50 So what happens is that the viruses aren't able to spread out.

01:55 Now these are active against both influenza A and influenza B.

01:59 And they're actually also each H1N1 influ.

02:03 If you remember that made some headlines a few years ago.

02:06 It's also active against H3N2 influenza virus as well.

02:12 Worldwide resistance is actually quite rare.

02:16 And we think that the worldwide resistance that does develop is due to mutations of the neuraminidases.