Ampicillin and Cloxacillin (Ampiclox)

Ampicillin exerts bactericidal action on both gm+ve and gm-ve organisms. Its spectrum includes gm+ve organisms eg, S pneumoniae and other Streptococci, L monocytogenes and gm-ve bacteria eg, M catarrhalis, N gonorrhoea, N meningitidis, E coli, P mirabilis, Salmonella, Shigella, and H influenzae. Ampicillin exerts its action by inhibiting the synthesis of bacterial cell wall. 

Cloxacillin is a penicillinase-resistant penicillin. It is active against gm+ve organisms including penicillinase-producing strains of Staphylococci. Cloxacillin is highly active against Staph aureus, Strep pyogenes, Strep viridans and Strep pneumoniae. It is also active against penicillinase-producing gonococci and against N meningitidis and H influenzae. Other gm-ve organisms are resistant to cloxacillin as are also methicillin-resistant strains of Staphylococci.

Indications for Ampicillin + Cloxacillin 

Ampicillin has a narrow spectrum of activity and is mainly active against Gram positive bacilli, both gram positive and Gram negative cocci and spirochaetes. Cloxacillin has a similar spectrum of activity to Penicillin and it is also active against penicillinase producing organisms such as Staphylococcus aureus

• Respiratory tract infection   
• Urinary tract infection   
• Bone and joint infection   
• Skin infection   
• Soft tissue infection

About Ampicillin

Semisynthetic Broad spectrum beta-lactam antibiotic, Aminobenzylpenicillin Antibiotic

Mechanism of Action of Ampicillin 

Ampicillin is a bactericidal drug. It is a Beta lactum antibiotic. It binds to the Penicillin binding protein in the cell wall of bacteria and inhibits the enzyme transpeptidase which is responsible for the transpeptidation reaction in peptidoglycan synthesis. It also activates the endogenous enzyme which degrades the peptidoglycan. These results in inhibition of protein synthesis and there by cell wall synthesis. Ampicillin is active against both gram positive and gram negative organism.

Onset of Action for Ampicillin: 30 minutes

Duration of Action for Ampicillin: 6 – 8 hours

Half Life of Ampicillin: 90 minutes

Side Effects of Ampicillin   

• Nausea   
• Vomiting   
• Diarrhoea   
• Anaphylaxis   
• Rash   
• Urticaria   
• Thrombocytopenia   
• Nephritis   
• Seizure.

Contra-indications of Ampicillin: Hypersensitivity to Penicillin

Special Precautions while taking Ampicillin   

1.Mononucleosis    2.Lymphatic leukaemia    3.HIV infections    4.Renal impairment

Pregnancy Related Information: Use with caution

Old Age Related Information: Use with caution

Breast Feeding Related Information: Use with caution

Indications for Ampicillin   

• Urinary tract infections   
• Gonorrhoea   
• Meningitis   
• SABE   
• Respiratory tract infections   
• Septicemia   
• Soft tissue infections   
• Otitis media   
• Sinusitis   
• Tetanus   
• Biliary tract infections   
• Bronchitis   
• Salmonellosis   
• Typhoid   
• Gastroenteritis   
• Cholecystitis   
• Paratyphoid fever

Interactions for Ampicillin

Oral contraceptives: Efficacy reduced, may cause breakthrough bleeding or pregnancy.   

Allopurinol: Increases risk of ampicillin induced skin rash.   

Beta blockers: Oral penicillin like ampicillin may reduce bio-availability of atenolol. Also they may potentiate anaphylatic reactions with penicillin.

Probenecid: Increases blood levels.   

Erythromycin, Tetracycline: Reduce efficacy.   

Clavulinic Acid: Synergy.   

Food: Interferes with absorption.

Typical Dosage for Ampicillin 

ADULT

Bacterial infections: 250 – 500 mg four times a day depending on the severity of infectionTyphoid and paratyphoid fever: 1 – 2 g four times daily

CHILDREN

Bacterial infections: 125 – 250 mg four times a day depending on the severity of infection

About Cloxacillin

It is a Penicillinase resistant Penicillin, Penicillin derived antibiotic.

Mechanism of Action of Cloxacillin 

Cloxacillin is a bactericidal drug. It binds to the Penicillin binding protein in the cell wall of bacteria and inhibits the enzyme transpeptidase which is responsible for the transpeptidation reaction in peptidoglycan synthesis. It also activates the endogenous enzyme which degrades the peptidoglycan. These results in inhibition of protein synthesis and there by cell wall synthesis. In addition to this it is not degraded by penicillinase enzyme and therefore it can be useful against penicillinase producing bacteria also.

Onset of Action for Cloxacillin: 30-60 minutes

Duration of Action for Cloxacillin: About 6 hours

Half Life of Cloxacillin: 30 minutes

Side Effects of Cloxacillin   

• Anaphylaxis   
• Rash   
• Urticaria   
• Thrombocytopenia   
• Seizure

Contra-indications of Cloxacillin

Hypersensitive to Cloxacillin or other Penicillins.

Special Precautions while taking Cloxacillin   

• Heart failure   
• Uremia   
• Hypokalemia   
• Bleeding tendencies   
• Meningitis   
• Renal impairment

Pregnancy Related Information: Use with caution
Old Age Related Information: Use with caution

Breast Feeding Related Information: Use with caution

Indications for Cloxacillin   

• Urinary tract infections   
• Respiratory tract infections   
• Septicemia   
• Osteomyelitis   
• Endocarditis   
• Pneumonia   
• Sinusitis   
• Bronchiectasis

Interactions for Cloxacillin

Oral contraceptives: Efficacy reduced, may cause breakthrough bleeding or pregnancy.

Atenolol: Bio-availability of atenolol reduced.

Allopurinol: Increases risk of cloxacillin induced skin rash.

Probenecid: Increases blood levels.

Erythromycin & Tetracyclines: Reduce efficacy.

Clavulanic Acid: Synergy.

Food: Interferes with absorption

Typical Dosage for Cloxacillin 

ADULT: 1 – 2 g daily in four divided dose depending on the severity of infection 

CHILDREN:   50 – 100 mg/kg/day in four divided dose depending on the severity of infection