Thursday, February 10, 2022

Ampicillin: Uses, Indications, Dosages, Precautions, Contraindications, Side Effects & Interactions

Ampicillin: Uses, Indications, Dosages, Precautions, Contraindications, Side Effects & Interactions


Pharmacotherapeutic: Penicillin
Clinical: Antibiotic
Pregnancy Risk Category: C
Do not confuse:
ampicillin with aminophylline, Omnipen with imipenem

General Information

Ampicillin belongs to the penicillin group of the antibiotic group. They are highly effective against severe infections caused by gram-positive and some gram-negative organisms (eg, respiratory tract, skin and skin structure, gastrointestinal and GU, bacterial meningitis, endocarditis, listeriosis, septicemia). It is not effective against penicillinase-producing staphylococci. Ampicillin is sometimes used to prevent bacterial endocarditis in surgical or instrumental interventions of the respiratory and dental tract. Prevention of bacterial endocarditis in gastrointestinal, GU, or biliary surgery or instrumentation. Used concurrently with gentamicin and used during labor, for the treatment of prevention of neonatal group B streptococcal infections

Ampicillin can cause severe reactions, such as: antibiotic associated colitis, other superinfections (abdominal cramps, severe watery diarrhea, fever) can result from an altered bacterial balance in the gastrointestinal tract. Severe hypersensitivity reactions, including anaphylaxis, acute interstitial nephritis, occur rarely


A penicillin that inhibits bacterial cell wall synthesis. The rigid, cross-linked cell wall is assembled in several steps. Ampicillin exerts its effects on sensitive bacteria in the final stage of the crosslinking process by binding and inactivating penicillin binding proteins (enzymes responsible for binding of cell wall strands). This action causes the lysis and death of bacterial cells

Therapeutic Effect

Bactericidal in susceptible microorganisms

Availability (Rx)

Capsules: 250 mg, 500 mg
Powder for Oral Suspension: 125 mg/5 mL, 250 mg/5 mL
Powder for Injection:125 mg, 250 mg, 500 mg, 1 g, 2 g


Infections of respiratory tract, skin, skin structures, GI/GU tract; otitis media, meningitis, septicemia, sinusitis, and endocarditis prophylaxis
Unlabeled uses: Biliary tract infection, shigellosis, typhoid fever, PID, OB/GYN infections, leptospirosis, Surgical prophylaxis for liver transplantation


Pregnancy B, breastfeeding, neonates, hypersensitivity to cephalosporins, renal disease, mononucleosis

Make sure to tell your doctor if:
• You have heart problems
• You have long-term liver or kidney problems
• You have hypersensitivity 
• You are taking other medicines

Indications and Dosages

‣ To Treat Respiratory tract, skin, and skinstructure infections

 Adults, Elderly, Children weighing more than 40 kg: 250-1000 mg q6h
 Children weighing < 20 kg: 50-100 mg/kg/day in divided doses q6h
 Adults, Elderly, Children weighing more than 40 kg: 500-1000 mg q6h
 Children weighing < 40 kg: 25-50 mg/kg/day in divided doses q6h

‣ To Treat Bacterial meningitis, septicemia

• Adults, Elderly: 150-200 mg/kg/day in divided doses, q3-4hr; IDSA IV 12 g divided q4hr
• Children: 150-200 mg/kg/day in divided doses q3-4hr; IDSA dose IV 300 mg/kg/ day divided q6hr
• Neonate  >7 days and >2000 g: 200 mg/kg/day divided q6hr; IDSA dose IV 200 mg/ kg/day divided q6-8hr

‣ To prevent of bacterial endocarditis from dental, oral, or upper respiratory tract procedures

• Adult: 2 g 30 min before procedure 
• Child: 50 mg/kg 30 min before procedure, max 2 g

‣ To Treat Uncomplicated gonococcal infections

• Adults: 3.5 g one time with 1 g probenecid

‣ To Treat Perioperative prophylaxis

• Adults, Elderly: 2 g 30 min before procedure. May repeat in 8 h
• Children: 50 mg/kg 30 min before procedure. May repeat in 8 h

‣ To Treat Gonorrhea (urethritis)

• Adult and children ≥45 kg: 3.5 g given with 1 g probenecid as a single dose (not recommended by CDC)

‣ Usual neonatal dosage

• Neonates 7-28 days old: 75 mg/kg/ day in divided doses q8h up to 200 mg/kg/day in divided doses q6h
• Neonates 0-7 days old. 50 mg/kg/day in divided doses q12h up to 150 mg/ kg/day in divided doses q8h

‣ Usual neonatal dosage

• Adult, children: CCr 10-50 ml/min extend to q6-12hr; CCr ,10 ml/min dose q12-24hr; Hemodialysis 1–2 g q12–24h; Peritoneal dialysis 250 mg q12h;  Continuous renal replacement therapy (CRRT) 2g, then 1–2 g q6–8h

‣ Dosage in Hepatic Impairment

 No dose adjustment


Moderately absorbed from the GI tract. Protein binding: 28%. Widely distributed. Partially metabolized in the liver. Primarily excreted in urine. Removed by hemodialysis. Half-life: 1-1.5 h (increased in impaired renal function)


PO route

• Give in even doses around the clock; product must be taken for 10-14 days to ensure organism death and prevent superinfection; store caps in tight container; store after reconstituting in refrigerator up to 2 wk, 1 wk room temperature
• Tabs may be crushed or caps opened and mixed with water
• Shake susp well before each dose; store for 2 wk in refrigerator or 1 wk at room temperature

IM route (painful)

• Reconstitute with 125 mg/0.9-1.2 ml; 250 mg/0.9-1.9 ml; 500 mg/1.2-1.8 ml; 1 g/2.4-7.4 ml; 2 g/6.8 ml
• Give deep in large muscle mass

IV route

• Reconstitute with 125 mg/0.9-1.2 ml; 250 mg/0.9-1.9 ml; 500 mg/1.2-1.8 ml; 1 g/2.4-7.4 ml; 2 g/6.8 ml
Direct IV route
• Give over 3-5 min in lower dosages (125-500 mg) or over 15 min in higher dosages (1-2 g)
Intermittent IV infusion route
• Give after diluting with 0.9% NaCl, LR, D5W, D5/0.45% NaCl; use 50 ml of sol and dilute to concentration of ,30 mg/ml


Hypersensitivity to any penicillin
Cautions: History of allergies, esp. cephalosporins, renal impairment, asthmatic patients, infectious mononucleosis


Individual drugs

• Allopurinol: increased ampicillin-induced skin rash, monitor for rash
• Probenecid: increased ampicillin levels, decreased renal excretion

Drug classifications

• Contraceptives (oral): decreased contraceptive effectiveness; use reliable contraception H2 antagonists, proton pump inhibitors: decreased ampicillin level
 Oral anticoagulants: increased bleeding, monitor INR/PTT

Drug/laboratory tests

• Increased: eosinophil, serum ALT, AST. May cause positive Coombs’ test
 Decreased: conjugated estrone in pregnancy, conjugated estriol, Hgb, WBC, platelets
 False positive: urine glucose
 Interfere: urine glucose (Clinitest, Benedict’s reagent, cupric SO4)


• None known


• None significant

Side effects

CNS: Chills, fatigue, fever, headache, malaise
CV: Chest pain, edema, thrombophlebitis
EENT: Epistaxis, glossitis, laryngeal stridor, mucocutaneous candidiasis, stomatitis, throat tightness
GI: Abdominal distention, diarrhea, diarrhea related to Clostridium difficile, enteroenterocolitis, flatulence, gastritis, nausea, pseudomembranous colitis, vomiting
GU: Dysuria, urine retention, vaginal candidiasis
HEME: Agranulocytosis, anemia, eosinophilia, leukopenia, thrombocytopenia, thrombocytopenic purpura
SKIN: Erythema multiforme; erythematous, mildly pruritic maculopapular rash or other types of rash; exfoliative dermatitis; pruritus; urticaria
Other: Anaphylaxis, facial edema, injection site pain

Nursing considerations

Baseline assessment

• Question for history of allergies, esp. penicillins, cephalosporins; renal impairment


• Promptly report rash (although common with ampicillin, may indicate
hypersensitivity) or diarrhea (fever, abdominal pain, mucus and blood in stool
may indicate antibiotic-associated colitis)
 Evaluate IV site for phlebitis
 Check IM injection site for pain, induration
 Monitor I&O, urinalysis, renal function tests. Be alert for superinfection: fever, vomiting, diarrhea, anal/genital pruritus, oral mucosal changes (ulceration, pain, erythema)

Equipment must be available for anaphylaxis

• Assess patient for previous sensitivity reaction to penicillins or other cephalosporins; crosssensitivity between penicillins and cephalosporins is common
• Assess patient for signs and symptoms of infection, including characteristics of wounds, sputum, urine, stool, WBC .10,000/mm3, earache, fever; obtain baseline information and during treatment
• Obtain C&S before beginning product therapy to identify if correct treatment has been initiated
• Assess for allergic reactions: rash, urticaria, pruritus, chills, fever, joint pain; angioedema may occur a few days after therapy begins; epinephrine and resuscitation equipment should be on unit for anaphylactic reaction; also, check for ampicillin rash: pruritic, red, raised; identify allergies before using Identify urine output, hematuria; if decreasing, notify prescriber (may indicate nephrotoxicity)
• Monitor renal studies: urinalysis, protein, blood, BUN, creatinine
• Monitor blood studies: AST, ALT, CBC, Hct, bilirubin, LDH, alkaline phosphatase, Coombs’ test monthly if patient is on long-term therapy
• Monitor electrolytes: potassium, sodium, chloride monthly if patient is on long-term therapy
• Assess bowel pattern daily; if severe diarrhea occurs, product should be discontinued; may indicate pseudomembranous colitis
• Assess for overgrowth of infection: perineal itching, fever, malaise, redness, pain, swelling, drainage, rash, diarrhea, change in cough, sputum


Positive therapeutic result
• Absence of signs/symptoms of infection (WBC ,10,000, temp WNL)
• Reported improvement in symptoms of infection

Patient/family teaching

• Tell patient to take dose with 8 oz of water 30 minutes before or 2 hours after meals
• Tab may be crushed; cap may be opened and mixed with water
• Instruct patient to take all medication prescribed for the length of time ordered
• Advise patient to contact prescriber if vaginal itching, loose foul-smelling stools, furry tongue occur; may indicate superinfection
• Tell patient to discomfort may occur with IM injection.
• Instruct patient to shake suspension well before each use, keep bottle tightly closed between uses, and discard unused portion after 14 days if refrigerated or 7 days if stored at room temperature.
• Review signs of allergic reaction; if they occur, tell patient to hold next ampicillin dose and contact prescriber immediately.
• Advise patient to notify prescriber of diarrhea with blood or pus, which may indicate pseudomembranous colitis
• Teach patient to report sore throat, bruising, bleeding, joint pain; may indicate blood dyscrasias (rare)

Treatment of Anaphylaxis:

Withdraw product, maintain airway, administer epinephrine, aminophylline, O2, IV corticosteroids

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