Case Study – Antiviral Drugs

00:00 Let's move on to some questions.

00:03 A 63 year old hemophiliac had contracted hepatitis B from contaminated blood products in the 1980's.

00:11 He stopped his medications against medical advice three months ago.

00:15 And presents now with fulminant transaminitis and jaundice.

00:19 The following are true statements about Hepatitis B in medications.

00:25 A. Interferon alpha acts through tyrosine kinase receptors.

00:29 B. Interferon alpha is quickly absorbed at the injection site.

00:34 C. Interferon alpha inhibits ribonuclease that degrades viral messengerRNA.

00:40 And D. Interferon alpha promotes the formation of natural killer cells.

00:46 So find the true statement.

00:51 Fantastic, you picked D.

00:53 Interferon alpha promotes the formation of natural killer cells.

00:59 Let's move on to the next question.

01:01 A 45 year old male has contracted influenza B.

01:05 The following statements are true: A. Zamanivir is an intranasal spray that may be beneficial for this patient if taken within 24 hours of the onset of symptoms.

01:16 B. Amantadine may be used as a prophylaxis for this patient.

01:20 C. Rimantadine may be beneficial for this patient if taken within 24 hours of the onset of symptoms.

01:28 D. Amantadine is an inhibitor of neuraminidase.

01:32 or E. Zamanivir which acts through blockage of a proton port in the cell wall that prevents acidification of the interior of the virus.

01:45 The answer is A.

01:46 Zamanivir is an intranasal spray that may be beneficial for this patient if taken within 24 hours of the onset of symptoms.

01:53 D is incorrect because amantadine is a blocker of a proton pump in the vesicle wall, that would have allowed transcription with an acidic environment.

02:02 E is incorrect because zamanivir is a neuraminidase inhibitor.

02:07 It does not act on a proton port.

02:09 Therefore, the correct answer is A.

02:14 Let's go on to another question.

02:17 A 34 year old male represents with a painful left eye.

02:21 He has a loss of vision in the left visual field.

02:24 The funduscopic image is displayed on the following slide.

02:28 So there you have the funuscopic image.

02:31 Now let's take a look at our choices here.

02:35 The appropriate treatment for this patient would be A. Valganciclovir 900 mg orally twice a day for 21 days and then once a day.

02:47 B. An intravitreal injection of ganciclovir or foscarnet over 7 to 10 days, then valganciclovir 900 mg twice a day for 21 days or resolution.

03:00 C. Ganciclovir 5mg per kilogram intravenous every 12 hours for 21 days.

03:09 Or D. Oral valganciclovir 900 mg twice a daily for 7 days.

03:16 Which is the right choice? You chose B.

03:22 The intravitreal injection of ganciclovir or foscarnet over 7 to 10 days, then oral valganciclovir 900 mg twice daily for 21 days or until resolution.

03:35 Now for some reason, this type of question always shows up on boards.

03:43 I've seen it when I was doing my undergraduate exams, it showed up again for my licensing exams, it showed up again for my internal medicine boards, and it showed up once again for my recertification exams. So we see it over and over and over again in multiple exam formats. So exam boards love CMV retinitis.

04:01 It's a very good disease to know.

04:04 Now remember that this patient is having a retinitis that is threatening his optic nerve, he has loss of vision, so it's very important to know that systemic therapy is not enough in this situation.

04:16 So we want to give an intravitreal injection of a strong antiviral like ganciclovir, and we give it usually every second day for 7 to 10 days. It's followed then by systemic therapy. So that's where oral ganciclovir can be used for 21 days, or alternatively we can use venous ganciclovir for 21 days too. Now, treatment is obviously under an eye specialist. This is not something that we manage in a general practitioner's clinic. Now, we also have something called ganciclovir intraocular implants. These are teeny tiny little pledgets that are very hard to see with a naked eye and they're inserted inside the vitreal cavity or beside the vitreal cavity and those are obviously put in by an eye surgeon as well. Those are very very effective too for CMV retinitis. That's it for our questions I'm sure you're going to do really well.

05:11 Show them what you know.