Drugs clinical

Question 1

TReatment of CA pneumonia

Home or admitted to hospital (but not severe, social/other admission with CAP, or no previous therapy)

Answer 1

Amoxicillin 0.5g-1.0g tds

OR Erythromycin

OR Clarithromycin

OR Doxycycline

Question 2

TReatment of CA pneumonia NOT SEVERE

IN HOSPITAL

Answer 2

Amoxicillin 0.5-1g tds AND [Erythromycin OR Clarithromycin OR Doxycycline]

All oral because not severe

Note: Hospitals tend to use amox + doxycyline because macrolides promote MRSA by selection. Modify therapy if blood cultures etc positive.

Question 3

SEVERE CAP

treated in HOSPITAL

Answer 3

•Co-amox 1.2g tds… IV

_AND _

Doxycycline orally OR [Erythromycin OR Clarithromycin] IV

Can ADD Rifampicin if severe Legionnaires’ disease OR Levofloxacin 0.5 g od plus Ben Pen 1.2 g qds

Question 4

Early HAP or Aspiration pneumonia e.g. post-op chest infection/pneumonia

Answer 4

AS FOR CAP

Question 5

Late HAP or Late Aspiration pneumonia

Answer 5

Piperacillin-tazobactam [‘Tazocin’],

plus dose of gentamicin if severe sepsis/shock

•Severely compromised patients - case by case management

Question 6

ANTIBIOTICS: FIRST DOSE

typical meningo rash

Bacterial meningitis

Answer 6

2.4g Ben Pen IV 4 hrly

Question 7

no typical rash & 18-50 y

ANTIBIOTICS: FIRST DOSE

bacterial maningitis

Answer 7

2g cefotaxime 6 hrly

OR

2 g ceftriaxone 12 hrly

Question 8

Antibiotics first dose:

DELAYED LP or Pen-resistant Pneumococcis risk

bacterial meningitis

Answer 8

add vanc or rifamp to cephalosporin (d/w Micro)

>50 y

consider adding Ampicillin or Amox 2g 4 hrly

Question 9

meningitis

ANTIBIOTISC FIRST DOSE IF

ANAPHYLAXIS TO BETA-LACTAMS

Answer 9

Chloramphenicol + vancomycin;

       **ADD ** *cotrimoxazole* for \> 50y

Question 10

GANCICLOVIR mode of action

Answer 10

Active form phosphorylated (GCV-P)

CMV UL97 gene product >> GCV-P

GCV-P >> GCV-PPP by cell

oral absorption only 5%

with added valine ir increases to 60%

Question 11

aciclovir mode of action

Answer 11

for VZV, herpes simplex

ACV-PPP inhibits viral DNA polymerase

ACV is selectively activated by thymidine kinase > it adds Pi: ACV-P

ACV-P >> ACV-PPP (phosphates added by cellular enzymes)

Nucleoside analogue
Active in triphosphate form
Requires viral thymidine kinase activity to addfirst PO4
2- group
Competitive substrate for viral DNA polymerase
Preferentially, irreversibly incorporated into growing DNA chain
Inhibits viral DNA polymerase
Obligatory chain terminator

Question 12

issues with aciclovir

modified structure

resistance

Answer 12

• Oral Bioavailability only 15 – 30% & Poor oral absorption
• Plasma Half-life 3 hour
• Frequent oral dosing required; 5 x per day
• 85% of drug excreted unchanged in urine
• Problem if renal impaired
• Nephrotoxicity due to precipitation in renal tubules
• CNS toxicity

added valine ester to aciclovir => VALACICLOVIR

1g tds of Valaciclovir comparable blood level as iv Aciclovir 5mg/kg tds

Common: Virus thymidine kinase absent
or
altered substrate specificity

Rarely: Virus DNA polymerase altered substrate specificity