L 34 Flashcards
Risk factors for UTIs
Female sex, age, dehydration, diabetes, pregnancy, kidney stones, UT obstruction
What are the Signs and symptoms of complicated UTIs (e.g pyelonephritis)
Systemic signs/symptoms e.g fever, chills, flank pain, nausea, vomiting, elevated WBC count
What are the Signs and symptoms for uncomplicated UTIs
Urinary frequency, urinary urgency, dysuria, suprapubic pain, nocturia (waking up at night to pee)
Do older patients present with the same UTI symptoms? Why/why not?
No, they have a naturally impaired immune system, so may present with altered mental status, poor appetite, incontinence etc
What is the diagnosis of UTIs based on?
Based on signs, symptoms and urine culture if necessary.
What are the Goals of UTI therapy (x4)?
- Eradicate causative pathogen
- Prevent or treat consequences of infection
- Administer appropriate empiric antimicrobial therapy or target therapy based on culture results
- Prevent recurrence of infection
What is the main pathogen of uncomplicated 80% uTIS and complicated 50% UTIs?
E.Coli
Where do they often come from?
Most often: E.coli (gram -ve)
Less common gram -ves: klebsiella pneumonia, proteus
Less common gram +ves: Staph and enterococcus
Pathogens often originate from the perirectal area
What are some examples of 2 resistant bacteria that can cause UTIs?
Enterobacter and pseudomonas aeruginosa species
What does the evidence look like for non-pharmacological/alternative UTI treatments? What
are some examples of these treatments?
Though the Evidence is patchy/uncertain.
e.g cranberry juice, alkalinisers, Hiprex
Pharmacological treatments for UTIs
Do you want a narrow or wide therapeutic index?
Antimicrobial therapy.
Wide therapeutic index
Name 3 general approaches that might be used to determine what dose to prescribe for a patient?
- Population method: Give everyone the same dose
- Covariate-based dosing: Base the dose on patient characteristics (e.g weight, renal function, sex etc)
- Dose-individualisation/response based: Dose based on response (adjusted for effect)
Name 6 common oral pharmacological treatment options (class + example) for UTIs. which is first line?
Which doesn’t reach adequate concentrations in renal impairment patients?
- Penicillins (e.g amoxicillin)
- Cephalosporins (e.g cefalexin)
- Fluoroquinolones (e.g norfloxacin)
- Nitrofurantoin
- Trimethoprim-sulfamethoaxazole
- Trimethoprim
First line: Trimethoprim
Nitrofurantoin doesn’t reach adequate concentration in the urine in renal impairment patients.
Name 5 common intravenous pharmacological treatment options for UTIs (class + example)
Which is first line?
- Penicillins (e.g amoxicillin)
- Aminoglycosides (e.g gentamicin)
- Cephalosporins (e.g cefuroxime)
- Fluoroqiunolones (.g ciprofloxacin)
- Carbapenems (e.g meropenem)
First line = gentamicin, narrow Tx window, dosed 24 hourly
Which tissues have the highest concentrations?
What is t1/2, how are metabolites cleared?
- Inhibits bacterial dihydrofolate reductase
- Gram +ve and -ve bacteria
- Yes, emerging resistance
- Urine, CNS, sputum, bile have highest concs.
- t1/2 = 11 hours, metabolites cleared renally
Uncomplicated UTI dosing of trimethoprim.
When is trimethoprim contraindicated?
300mg nocte 3/7 (men = 7 days)
Contraindicated if CLcr <10mL/min (V. LOW)
What medications/natural products have interactions with trimethoprim?
Warfarin, phenytoin, digoxin, creatinine
What medication is trimethoprim often combined with?
Trimethoprim + sulfamethoxazole
Common side effects of trimethoprim
Hyperkalaemia, GI disturbances
What are the indications for aminoglycosides?
Serious infections due to aerobic gram-negative bacilli
What are the General gentamicin dose?How is Gentamicin delivereD?
5-7mg/kg (kg = IBW), given OD
IV infusion over 30 mins
How is gentamicin cleared and eliminated?
Is it metabolized?
Cleared renally (NOT METABOLISED) Eliminated into urine
Peak serum concentration of gentamicin occurs at…
Peak serum concentration of gentamicin occurs at the end of the infusion
Serum concentrations of gentamicin at the end of the dos interval (… hours) are ….?
Serum concentrations of gentamicin at the end of the dos interval (24 hours) are almost unmeasurable
Is gentamicin a time-dependent or concentration-dependent drug?
Therefore what is important?
Concentration-dependent killer.
Dose is important
For gentamicin, a higher …. means a …. bacterial kill and a …. bacterial kill?
For gentamicin, a higher Cmax means a greater bacterial kill and a faster bacterial kill
Name three factors that might be expected to predict variability in dose requirements between patients (x5)?
- ADHERENCE
- Drug interactions
- Weight differences
- Renal function differences
- Genetic differences
Gentamicin has a … therapeutic window. What does this mean?
Gentamicin has a narrow therapeutic window. This means that there is a small concentration range here the drug has a high probability of being effective and a low probability of producing side effects.
Potential side effects of gentamicin?
Ototoxicity and nephrotoxicity
Give 2 examples of B lactams?
Do they have a wide or narrow therapeutic range?
Is dose adjustment therefore required between patients?
B lactam examples: penicillins, cephalosporins.
B lactams have a wide therapeutic range.
Dose requirements are less variable between patients but dose adjustment can still be required (e.g renal failure, obesity etc)
What is the first dose of gentamicin based on?
What about the subsequent doses?
1st dose: based on IBW
Subsequent doses are adjusted based on target exposure and renal function (dose-response based therapy for optimized efficacy and safety)
