Cefalexin

J01D - Other beta-lactam antibacterials ATC J01DB01 Small molecule approved 1971 Oral Natural product

🧬 Cross-allergy: Cephalosporins

JFDA label: Ramoxin-250 suspension

Mechanism of Action

Inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins (PBPs) which in turn inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls, thus inhibiting cell wall biosynthesis. Bacteria eventually lyse due to ongoing activity of cell wall autolytic enzymes (autolysins and murein hydrolases) while cell wall assembly is arrested.

Indications

Approved

Bone infections
Genitourinary tract infections
Otitis media
Respiratory tract infections
Skin and skin structure infections

Off-label

Community-acquired pneumonia (children)
Endocarditis, prophylaxis
Prosthetic joint infection

Antimicrobial Spectrum

Expected / intrinsic spectrum (EUCAST breakpoints & labels) — not local resistance. Source: EUCAST v16 · curated · openfda-label.

Bacteria

Organism	Activity	MIC
Acinetobacter calcoaceticus	Active	—
Enterobacterales	Susceptible	16.0 mg/L
Escherichia coli	Susceptible	8.0 mg/L
Haemophilus influenzae	Active	—
Klebsiella pneumoniae	Active	—
Moraxella catarrhalis	Active	—
Morganella morganii	Active	—
Proteus mirabilis	Active	—
Proteus vulgaris	Active	—
Staphylococcus aureus	Susceptible	1.0 mg/L
Streptococcus pneumoniae	Active	—
Streptococcus pyogenes	Susceptible	0.5 mg/L
Staphylococcus aureus	Resistant	1.0 mg/L

Class profile

gramStatus	Both
spectrumBreadth	Moderate
atypicalCoverage	No
isBactericidal	1
moaCategory	Cell wall synthesis inhibitor (beta-lactam, 1st generation cephalosporin)
pdIndex	Time-dependent
postAntibioticEffect	None
mrsaCoverage	0
resistanceMechanisms	Beta-lactamase production,PBP mutations

Contraindications

Source: Lexicomp

Hypersensitivity to cephalexin, other cephalosporins, or any component of the formulation Absolute

Adverse Reactions

Very Common >10%Common 1–10%Uncommon 0.1–1% Rare 0.01–0.1%Very Rare <0.01%Not Known

Nervous system disorders (6)

Not Known Agitation · confusion · dizziness · fatigue · hallucination · headache

Hepatobiliary disorders (4)

Not Known Cholestatic jaundice (rare) · hepatitis (transient, rare) · increased serum ALT · increased serum AST

Renal and urinary disorders (4)

Not Known Genital candidiasis · Interstitial nephritis (rare) · vaginal discharge · vaginitis

Blood and lymphatic system disorders (4)

Not Known Eosinophilia · hemolytic anemia · neutropenia · thrombocytopenia

Immune system disorders (4)

Uncommon Allergic reaction

Not Known Anaphylaxis · angioedema · hypersensitivity reaction

Gastrointestinal disorders (9)

Common Diarrhoea · Nausea

Not Known Abdominal pain · diarrhea · dyspepsia · gastritis · nausea (rare) · pseudomembranous colitis · vomiting (rare)

Skin and subcutaneous tissue disorders (7)

Uncommon Rash

Not Known Erythema multiforme (rare) · genital pruritus · skin rash · Stevens-Johnson syndrome (rare) · toxic epidermal necrolysis (rare) · urticaria

Musculoskeletal and connective tissue disorders (3)

Not Known Arthralgia · arthritis · arthropathy

Investigations (1)

Uncommon Elevated serum creatinine

Dosing

Source: Lexicomp

Usual dosage range: Oral: 250 to 1,000 mg every 6 hours or 500 mg every 12 hours (maximum: 4 g/day) Indication-specific dosing: Cellulitis (nonpurulent)/erysipelas, mild (alternative agent): Oral: 500 mg 4 times daily for at least 5 days (duration should be extended if not resolved/slow response) (IDSA [Stevens 2014]) Cystitis, uncomplicated (alternative agent): Oral: 500 mg every 12 hours for 5 to 7 days (Hooton 2018) Endocarditis, prophylaxis (dental or invasive respiratory tract procedures; alternative agent) (off-label use): Oral: 2 g 30 to 60 minutes prior to procedure. Note: American Heart Association (AHA) guidelines recommend prophylaxis only in patients undergoing invasive procedures and in whom underlying cardiac conditions may predispose to a higher risk of adverse outcomes should infection occur (AHA [Wilson 2007]). Impetigo or ecthyma: Oral: 250 to 500 mg 4 times daily for 7 days. Note: Not an appropriate agent if MRSA is suspected or confirmed (Baddour 2018; IDSA [Stevens 2014]). Pharyngitis, streptococcal (alternative agent): Oral: 500 mg every 12 hours for 10 days (IDSA [Shulman 2012]) Prosthetic joint infection (off-label use): Oral: Treatment (following pathogen-specific IV therapy in patients undergoing 1-stage exchange or debridement with retention of prosthesis). Note: Duration ranges from a minimum of 3 months to indefinitely, depending on patient-specific factors (Berbari 2018): Staphylococci (methicillin-susceptible): 500 mg every 6 to 8 hours. For the first 3 to 6 months of therapy, combine with rifampin (Berbari 2018; IDSA [Osmon 2013]). Streptococci, beta-hemolytic (alternative agent): 500 mg every 6 to 8 hours (Berbari 2018; IDSA [Osmon 2013]) Cutibacterium spp (alternative agent): 500 mg every 6 to 8 hours (IDSA [Osmon 2013]; Kanafani 2018)

(For additional information see "Cephalexin: Pediatric drug information") Usual dosage range: Children >1 year and Adolescents Adolescents ≥ 15 years: Oral: 250 to 1,000 mg every 6 hours; maximum daily dose: 4 g/day Indication-specific dosing: Community-acquired pneumonia (CAP) (IDSA/PIDS 2011), S. aureus (methicillin-susceptible), mild infection or step-down therapy (preferred) (off-label use): Infants >3 months and Children: Oral: 75 to 100 mg/kg/day in 3 to 4 divided doses Cystitis, uncomplicated: Adolescents ≥15 years: Refer to adult dosing. Endocarditis, prophylaxis (dental, oral, or invasive respiratory tract procedures) (off-label use): Infants, Children, and Adolescents: Oral: 50 mg/kg 30 to 60 minutes prior to procedure (maximum dose: 2 g). Note: American Heart Association (AHA) guidelines now recommend prophylaxis only in patients undergoing invasive procedures and in whom underlying cardiac conditions may predispose to a higher risk of adverse outcomes should infection occur (AHA [Wilson 2007]). Impetigo: Children: Oral: 25 to 50 mg/kg/day in 3 to 4 divided doses; continue for 7 days, depending upon clinical response (IDSA [Stevens 2014]) Otitis media: Children: 75 to 100 mg/kg/day in 4 divided doses Pharyngitis, streptococcal: Children >1 year: Oral: 25 to 50 mg/kg/day divided every 12 hours. Note: Recommended by the Infectious Disease Society of America (IDSA) as an alternative agent for group A streptococcal pharyngitis in penicillin-allergic patients (avoid in patients with immediate-type hypersensitivity to penicillin) at a dose of 40 mg/kg/day divided twice daily (maximum: 1000 mg daily) for 10 days (Shulman 2012). Severe infections: Children: Oral: 50 to 100 mg/kg/day in divided doses every 6 to 8 hours Skin and skin structure infections: Manufacturer’s labeling: Children >1 year and Adolescents Adolescents ≥15 years: Refer to adult dosing. Alternate recommendations: Children: 25 to 50 mg/kg/day divided every 6 hours (IDSA [Stevens 2014])

Refer to adult dosing.

Adolescents >15 years and Adults: CrCl ≥60 mL/minute: No dosage adjustment necessary. CrCl 30 to 59 mL/minute: There are no specific dosage adjustments provided in the manufacturer’s labeling; maximum recommended daily dose: 1,000 mg/day. CrCl 15 to 29 mL/minute: 250 mg every 8 to 12 hours CrCl 5 to 14 mL/minute (not yet on dialysis): 250 every 24 hours CrCl 1 to 4 mL/minute (not yet on dialysis): 250 mg every 48 to 60 hours End stage renal disease (ESRD) on intermittent hemodialysis: There are no dosage adjustments provided in the manufacturer’s labeling; however the following guidelines have been used by some clinicians (Aronoff 2007): Oral: 250 to 500 mg every 12 to 24 hours; moderately dialyzable (20% to 50%); give dose after dialysis session. Peritoneal dialysis: There are no dosage adjustments provided in the manufacturer’s labeling; however, the following guidelines have been used by some clinicians (Aronoff 2007): Oral: 250 to 500 mg every 12 to 24 hours.

There are no dosage adjustments provided in the manufacturer’s labeling.

Warnings & Precautions

Source: Lexicomp

Hypersensitivity

Allergic reactions (eg, rash, urticaria, angioedema, anaphylaxis, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis [TEN]) have been reported. If an allergic reaction occurs, discontinue immediately and institute appropriate treatment.

Elevated INR

May be associated with increased INR, especially in nutritionally-deficient patients, prolonged treatment, hepatic or renal disease.

Penicillin allergy

Use with caution in patients with a history of penicillin allergy, especially IgE-mediated reactions (eg, anaphylaxis, angioedema, urticaria).

Seizure disorder

Use with caution in patients with a history of seizure disorder; high levels, particularly in the presence of renal impairment, may increase risk of seizures.

Superinfection

Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea (CDAD) and pseudomembranous colitis; CDAD has been observed >2 months postantibiotic treatment. Disease-related concerns:

Renal impairment

Use with caution in patients with renal impairment; modify dosage in severe impairment. Concurrent drug therapy issues:

Drug-drug interactions

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information. Other warnings/precautions:

Direct Coombs tests

Positive direct Coombs tests and acute intravascular hemolysis has been reported. If anemia develops during or after therapy, discontinue use and work up for drug-induced hemolytic anemia.

Pregnancy & Lactation

Pregnancy

FDA category B

Safe

Commonly used for UTI and skin infections in pregnancy

Lactation

RID 0.13%

Cephalexin is excreted in breast milk. The relative infant dose (RID) of cephalexin is 0.13% to 0.52% when compared to an infant therapeutic dose of 25 to 100 mg/kg/day. In general, breastfeeding is considered acceptable when the relative infant dose is 25% breastfeeding should generally be avoided (Anderson 2016; Ito 2000). Using a milk concentration of 0.85 mcg/mL, the estimated daily infant dose via breast milk is 0.13 mg/kg/day. This milk concentration was obtained following a single mater

Monitoring

Efficacy	Culture and susceptibility testing; clinical resolution (temperature, WBC, CRP, procalcitonin)
Toxicity	Renal function (dose adjustment in renal impairment); hepatic function for hepatically cleared agents; signs of C. difficile infection (diarrhoea)
Clinical pearl	Culture results guide de-escalation to narrower-spectrum therapy. Review antibiotic appropriateness at 48–72 h (antimicrobial stewardship).
Counseling	Complete the full course. Report persistent diarrhoea, rash, or lack of improvement after 48–72 h.

Chemistry & Properties

Formula	C16H17N3O4S
Molecular weight	347.4 g/mol
IUPAC name	(6R,7R)-7-[[(2R)-2-amino-2-phenylacetyl]amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
CAS	15686-71-2
PubChem CID	27447
InChIKey	`ZAIPMKNFIOOWCQ-UEKVPHQBSA-N`
logP	0.44 (XLogP 0.6)
Polar surface area	112.73 Å²
H-bond acceptors / donors	5 / 3
Drug-likeness (QED)	0.68
Lipinski violations	0

SMILES

CC1=C(C(=O)O)N2C(=O)[C@@H](NC(=O)[C@H](N)c3ccccc3)[C@H]2SC1

Biology & Pharmacokinetics

Pharmacokinetics

BBB penetrant	No

Enzyme interactions

Enzyme	Role	Detail
CYP2D6	Substrate	—
CYP3A4	Substrate	—

Transporters

BCRP (Inhibitor)BSEP (Inhibitor)MRP1 (Inhibitor)OATP1B1 (Inhibitor)OATP1B3 (Inhibitor)P-gp (Inhibitor)P-gp (Substrate)

Registered Products (46)

Brand	Form / strength	Pack	Agent	Citizen (JOD)
Pharmexin suspention	Suspension 125 mg/5 ml	60 ml pack varies	Pharma International Company/ Jordan	1.000
Ramoxin-125 suspension	Suspension 125 mg/5 ml	60 ml pack varies	AL-RAM PHARMA.INDUS.CO.LTD/JORDAN	1.000
Felexin Suspension	Suspension 125 mg/5 ml	100 ml	JAWEDA INT. DRUD STORE	1.440
Ramoxin-250 suspension	Suspension 250 mg/5 ml	60 ml pack varies	AL-RAM PHARMA.INDUS.CO.LTD/JORDAN	1.500
OSPEXIN	Suspension 125 mg/5 ml	60 ml pack varies	Nabulsi Drug Store	1.530
Pharmexin suspention	Suspension 250 mg/5 ml	60 ml	Pharma International Company/ Jordan	1.540
Midaflex 125	Suspension 125 mg/5 ml	100 ml	MIDDLE EAST PHARMA&CHEMICAL IND/JORDAN	1.650
Pharmexin suspention	Suspension 125 mg/5 ml	100 ml pack varies	Pharma International Company/ Jordan	1.650
Ramoxin-125 suspension	Suspension 125 mg/5 ml	100 ml pack varies	AL-RAM PHARMA.INDUS.CO.LTD/JORDAN	1.660
CEPHADAR G.F.SUSP.	Suspension 125 mg/5 ml	100 ml	Dar Al Dawa Development and Investment Co Ltd/Jordan	1.690
Keflex	Suspension 250 mg/5 ml	60 ml	Dar Al Dawa Development and Investment Co Ltd/Jordan	1.990
Felexin Suspension	Suspension 250 mg/5 ml	100 ml	JAWEDA INT. DRUD STORE	2.220
Cefalix	Tablet 250 mg	20 tab	Al-Taqqadom Pharmaceutical Industries	2.250
Midaflex Capsules	Capsule 250 mg	20 cap pack varies	MIDDLE EAST PHARMA&CHEMICAL IND/JORDAN	2.470
Pharmexin	Tablet 250 mg	20 tab	Pharma International Company/ Jordan	2.470
CEPHADAR 250 CAPS.	Capsule 250 mg	20 cap pack varies	Dar Al Dawa Development and Investment Co Ltd/Jordan	2.500
Pharmexin	Suspension 250 mg/5 ml	100 ml	Pharma International Company/ Jordan	2.500
Ramoxin-	Capsule 250 mg	20 cap pack varies	AL-RAM PHARMA.INDUS.CO.LTD/JORDAN	2.500
Ramoxin-250 suspension	Suspension 250 mg/5 ml	100 ml pack varies	AL-RAM PHARMA.INDUS.CO.LTD/JORDAN	2.500
Lexin 250 Suspension	Suspension 250 mg/5 ml	100 ml	Hikma Pharmaceuticals Co.Ltd/Jordan	2.520
Midaflex Dry Suspension	Suspension 250 mg/5 ml	100 ml	MIDDLE EAST PHARMA&CHEMICAL IND/JORDAN	2.520
Unilexin 250 Dry Suspension	Suspension 250 mg/5 ml	100 ml	UNITED PHARM.MFG.CO.LTD(UPM)/JORDAN	2.520
OSPEXIN	Suspension 125 mg/5 ml	100 ml pack varies	Nabulsi Drug Store	2.560
CEPHADAR F. G.F.SUSP	Suspension 250 mg/5 ml	100 ml	Dar Al Dawa Development and Investment Co Ltd/Jordan	2.600
Lexin 500 Capsules	Capsule 500 mg	12 cap pack varies	Hikma Pharmaceuticals Co.Ltd/Jordan	2.820
MEDOLEXIN CAP	Capsule 250 mg	20 cap	Khoury Drug Store	3.300
CEPHADAR FORTE CAPS.	Capsule 500 mg	20 cap pack varies	Dar Al Dawa Development and Investment Co Ltd/Jordan	3.430
Cefalix	Tablet 500 mg	20 tab pack varies	Al-Taqqadom Pharmaceutical Industries	3.500
Keflex	Capsule 500 mg	12 cap pack varies	Dar Al Dawa Development and Investment Co Ltd/Jordan	3.530
Midaflex Capsules	Capsule 500 mg	20 cap pack varies	MIDDLE EAST PHARMA&CHEMICAL IND/JORDAN	3.900
Pharmexin cap	Capsule 500 mg	20 cap pack varies	Pharma International Company/ Jordan	3.900
FELEXIN 500 CAPS	Capsule as monohydrate 500 mg	20 cap	JAWEDA INT. DRUD STORE	3.910
Lexin 500 Capsules	Capsule 500 mg	20 cap pack varies	Hikma Pharmaceuticals Co.Ltd/Jordan	3.910
Ramoxin-	Capsule 500 mg	20 cap pack varies	AL-RAM PHARMA.INDUS.CO.LTD/JORDAN	3.910
Lexin 1000 Tablets	Tablet 1 g	12 tab pack varies	Hikma Pharmaceuticals Co.Ltd/Jordan	4.410
Keflex	Capsule 500 mg	20 cap pack varies	Dar Al Dawa Development and Investment Co Ltd/Jordan	5.700
Lexin 1000 Tablets	Tablet 1 g	18 tab pack varies	Hikma Pharmaceuticals Co.Ltd/Jordan	6.610
Lexin 1000 Tablets	Tablet 1 g	24 tab pack varies	Hikma Pharmaceuticals Co.Ltd/Jordan	9.510
Pharmexin cap	Capsule 500 mg	500 cap pack varies	Pharma International Company/ Jordan	35.050
CEPHADAR 250 CAPS.	Capsule 250 mg	500 cap pack varies	Dar Al Dawa Development and Investment Co Ltd/Jordan	40.430
Midaflex Capsules	Capsule 250 mg	500 cap pack varies	MIDDLE EAST PHARMA&CHEMICAL IND/JORDAN	50.640
CEPHADAR FORTE CAPS.	Capsule 500 mg	500 cap pack varies	Dar Al Dawa Development and Investment Co Ltd/Jordan	72.190
Cefalix	Tablet 500 mg	500 tab pack varies	Al-Taqqadom Pharmaceutical Industries	74.380
Midaflex Capsules	Capsule 500 mg	500 cap pack varies	MIDDLE EAST PHARMA&CHEMICAL IND/JORDAN	79.950
Ramoxin-	Capsule 250 mg	1000 cap pack varies	AL-RAM PHARMA.INDUS.CO.LTD/JORDAN	106.250
Ramoxin-	Capsule 500 mg	1000 cap pack varies	AL-RAM PHARMA.INDUS.CO.LTD/JORDAN	156.490