Phenoxymethylpenicillin (penicillin V)
Kåvepenin · Tikacillin · Fenoximetylpenicillin EQL Pharma
The first-choice oral penicillin for the most common respiratory and skin infections in outpatient care, and one of the reasons Sweden maintains a favourable resistance situation. The spectrum covers group A streptococci and pneumococci but not Haemophilus influenzae or staphylococci. Dosing differs substantially between indications — tonsillitis and acute otitis media are treated with different doses and durations, and this is a common source of error in practice.
Anaphylaxis occurs, though rarely. Always ask about previous penicillin reactions and distinguish true type I allergy from childhood rashes occurring during infection — the majority of patients reporting penicillin allergy tolerate penicillin.
Dosing in adults
| Indication | Regimen | Comment |
|---|---|---|
| Pharyngotonsillitis (Centor 3–4 + positive rapid strep test) | 1 g × 3 orally for 10 days; children 12,5 mg/kg × 3 for 10 days | do not treat Centor 0–2 and do not test them either |
| Acute otitis media | Children 25 mg/kg × 3 orally for 5 days; adults 1,6 g × 3 for 5 days | 10 days for recurrence or complicating factors |
| Community-acquired pneumonia, CRB-65 0–1 | 1 g × 3 orally for 7 days | 2 g × 3 if weight exceeds 90 kg |
| Erysipelas | 1 g × 3 orally for 10 days | 2 g × 3 if weight exceeds 90 kg; 10–14 days if slow regression |
| Acute rhinosinusitis with treatment indication | 1,6 g × 3 orally for 7–10 days | most sinusitis cases should not be treated with antibiotics |
No adjustment at eGFR above 30 ml/min. In severe renal impairment (eGFR below 30 ml/min) the dosing interval is extended or the daily dose reduced; risk of accumulation of the potassium salt in hyperkalaemia.
No dose adjustment. Eliminated predominantly renally.
12,5 mg/kg × 3 for pharyngotonsillitis and pneumonia, 25 mg/kg × 3 for acute otitis media and sinusitis. Maximum 1 g and 1,6 g per dose respectively. Available as oral suspension 50 and 100 mg/ml and as oral drops 250 mg/ml for the youngest children.
Wrong choice when Haemophilus influenzae or staphylococci are the likely pathogen: COPD exacerbation, sinusitis with treatment failure, wound infection, and impetigo are not covered by the spectrum. In tonsillitis with a Centor score of 0–2 neither a rapid test nor antibiotics should be used — the aetiology is viral.
Pharmacokinetics
- BIOAVAIL.
- approximately 50 % orally
- t½
- approximately 30 minutes
- PROTEIN BINDING
- approximately 80 %
- METABOLISM
- Negligible
- EXCRETION
- Renal, tubular secretion
- FOOD EFFECT
- Absorption reduced by food
- PK/PD INDEX
- T > MIC — hence three-times-daily dosing
- ONSET
- Peak serum concentration after 30–60 minutes