Formulary
Ampicillin: Indications, Dosing, Side Effects and Interactions
The penicillins are bactericidal and act by interfering with bacterial cell wall synthesis.
MedNext Academy | 5 min read
Ampicillin: Indications, Dosing, Side Effects and Interactions
The penicillins are bactericidal and act by interfering with bacterial cell wall synthesis.
Drug action
The penicillins are bactericidal and act by interfering with bacterial cell wall synthesis. They diffuse well into body tissues and fluids, but penetration into the cerebrospinal fluid is poor except when the meninges are inflamed. They are excreted in the urine in therapeutic concentrations.
Indications and dose
**Susceptible infections (including bronchitis, urinary-tract infections, otitis media, sinusitis, uncomplicated community-acquired pneumonia, salmonellosis)**
- **Child** (By Mouth): 12-17 years 500 mg 4 times a day, increased if necessary to 1 g 4 times a day, use increased dose in severe infection.
- **Adult** (By Mouth): 0.5-1 g every 6 hours.
- **Adult** (By Intravenous Injection, Or By Intravenous Infusion): 500 mg every 4-6 hours.
- **Adult** (By Intramuscular Injection): 500 mg every 4-6 hours.
**Endocarditis (in combination with another antibacterial if necessary)**
- **Adult** (By Intravenous Infusion): 2 g every 4 hours.
**Listerial meningitis**
- **Adult** (By Intravenous Infusion): 2 g every 4 hours.
**Susceptible infections (including bronchitis, urinary-tract infections, otitis media, sinusitis, uncomplicated community-acquired pneumonia, salmonellosis) for ampicillin**
- **Neonate 7 days to 20 days** (By mouth): 30 mg/kg 3 times a day (max. per dose 125 mg).
- **Neonate 21 days to 28 days** (By mouth): 30 mg/kg 4 times a day (max. per dose 125 mg).
- **Child 1-11 months** (By mouth): 125 mg 4 times a day, increased if necessary up to 30 mg/kg 4 times a day.
- **Child 1-4 years** (By mouth): 250 mg 4 times a day, increased if necessary up to 30 mg/kg 4 times a day.
- **Child 5-11 years** (By mouth): 500 mg 4 times a day, increased if necessary up to 30 mg/kg 4 times a day (max. per dose 1 g).
- **Child 12-17 years** (By mouth): 500 mg 4 times a day, increased if necessary to 1 g 4 times a day, use increased dose in severe infection.
- **Neonate up to 7 days** (By intravenous injection, or by intravenous infusion): 30 mg/kg every 12 hours, increased if necessary to 60 mg/kg every 12 hours, increased dose used in severe infection, community-acquired pneumonia or salmonellosis.
- **Neonate 7 days to 20 days** (By intravenous injection, or by intravenous infusion): 30 mg/kg every 8 hours, increased if necessary to 60 mg/kg every 8 hours, increased dose used in severe infection, community-acquired pneumonia or salmonellosis.
- **Neonate 21 days to 28 days** (By intravenous injection, or by intravenous infusion): 30 mg/kg every 6 hours, increased if necessary to 60 mg/kg every 6 hours, increased dose used in severe infection, community-acquired pneumonia or salmonellosis.
- **Child** (By intravenous injection, or by intravenous infusion): 25 mg/kg every 6 hours (max. per dose 500 mg), increased if necessary to 50 mg/kg every 6 hours (max. per dose 1 g), increased dose used in severe infection.
**Group B streptococcal infection, Enterococcal endocarditis (in combination with another antibacterial) for ampicillin**
- **Neonate up to 7 days** (By intravenous infusion): 50 mg/kg every 12 hours.
- **Neonate 7 days to 20 days** (By intravenous infusion): 50 mg/kg every 8 hours.
- **Neonate 21 days to 28 days** (By intravenous infusion): 50 mg/kg every 6 hours.
- **Child** (By intravenous infusion): 50 mg/kg every 4-6 hours (max. per dose 2 g).
**Listerial meningitis for ampicillin**
- **Neonate up to 7 days** (By intravenous infusion): 100 mg/kg every 12 hours.
- **Neonate 7 days to 20 days** (By intravenous infusion): 100 mg/kg every 8 hours.
- **Neonate 21 days to 28 days** (By intravenous infusion): 100 mg/kg every 6 hours.
- **Child** (By intravenous infusion): 50 mg/kg every 4-6 hours (max. per dose 2 g).
Cautions
History of allergy Cautions For ampicillin General cautions: Acute lymphocytic leukaemia (increased risk of erythematous rashes); chronic lymphocytic leukaemia (increased risk of erythematous rashes); cytomegalovirus infection (increased risk of erythematous rashes); glandular fever (erythematous rashes common) Specific cautions: With intravenous use Accumulation of electrolytes contained in parenteral preparations can occur with high doses
Side effects
Common or very common Diarrhoea; hypersensitivity; nausea; skin reactions; thrombocytopenia; vomiting Uncommon Arthralgia; leucopenia Rare or very rare Agranulocytosis; angioedema; haemolytic anaemia; hepatic disorders; nephritis tubulointerstitial; neutropenia; pseudomembranous enterocolitis; seizure; severe cutaneous adverse reactions (SCARs) Side-effects, further information Diarrhoea frequently occurs during oral penicillin therapy. It is most common with broad-spectrum penicillins, which can cause antibiotic-associated colitis. Side-effects For ampicillin Frequency not known Colitis haemorrhagic
Interactions
**Other interactions (4):**
- Peak concentrations of raloxifene are reduced with co-administration with ampicillin.
- However, since the overall extent of absorption and the elimination rate of raloxifene are not affected, raloxifene can be concurrently administered with ampicillin.
- Ampicillin/Amoxicillin An increase in frequency of skin rash has been reported among patients receiving ampicillin or amoxicillin concurrently with allopurinol compared to patients who are not...
- However, it is recommended that in patients receiving allopurinol an alternative to ampicillin or amoxicillin is used where available.
Pregnancy
Not known to be harmful.
Breast feeding
Trace amounts in milk, but appropriate to use.
Renal impairment
Rashes more common in renal impairment. Accumulation of sodium from injection can occur in patients with renal failure. Dose adjustments Consider dose reduction or increase dose interval if creatinine clearance less than 10 mL/minute, M see Prescribing in renal impairment .
Medicinal forms
Capsule,Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
Inside MedNext for this topic
- 411 MedNext-authored chapters
- 80,000+ MCQ bank
- 15 study modes
- Growing visual cheat sheets
Study modes
- Notes
- MCQ
- Audio
- Video
- Visual
- 3D Anatomy
- Trace
- Flashcards
- Mnemonics
- Image Bank
- Clinical
- Microscopy
- Audio QBank
- Cadaver
- Book Match
Continue reading
Subject HubPharmacology Hub
All pharmacology resources in one place.
Drug SchedulesIndian Drug Schedules
Schedule H, H1, X and G classifications.
FormularyBrowse all drugs
Search 1,850+ drug profiles.
Study Ampicillin in the MedNext app
Challenge yourself with targeted pharmacology MCQs on this drug class. Every explanation links back to the chapter that teaches the concept.
Start drug challengeExplore the full formulary