Usage
Amoxycillin + Dicloxacillin is prescribed for bacterial infections susceptible to this combination. This includes infections of the respiratory tract (e.g., tonsillitis, bronchitis, pneumonia, sinusitis), skin and soft tissue infections (e.g., cellulitis, abscesses), urinary tract infections (UTIs), ear infections (otitis media), heart infections (endocarditis), and dental infections.
Its pharmacological classification is antibiotic, specifically a beta-lactam antibiotic combining two penicillins.
The mechanism of action involves inhibiting bacterial cell wall synthesis, ultimately leading to bacterial cell death (bactericidal effect). Dicloxacillin is particularly useful against bacteria that produce beta-lactamases, enzymes that can break down amoxycillin.
Alternate Names
There is no internationally recognized non-proprietary name for this specific combination. However, the individual components are known as amoxicillin and dicloxacillin.
Brand names vary depending on the region and manufacturer. Some examples include Eeshmox-D, Novaclox, and Zexo-DC.
How It Works
Pharmacodynamics: Both amoxycillin and dicloxacillin are beta-lactam antibiotics that target penicillin-binding proteins (PBPs) on bacterial cell walls. These PBPs are crucial enzymes in the final stages of peptidoglycan synthesis, a vital component of the cell wall. By binding to and inhibiting these enzymes, these drugs prevent cross-linking of peptidoglycans, weakening the bacterial cell wall structure and causing cell lysis and death.
Pharmacokinetics: Amoxycillin is well-absorbed orally and achieves therapeutic concentrations in various tissues and fluids, including the respiratory tract, middle ear, and urine. Dicloxacillin is also well-absorbed orally, but its absorption can be slowed by food. Both drugs are primarily excreted by the kidneys. The half-life of dicloxacillin is increased in patients with renal failure.
Mode of Action: These antibiotics bind to and inhibit bacterial transpeptidases, carboxypeptidases, and endopeptidases. These enzymes, collectively called penicillin-binding proteins (PBPs), are responsible for the cross-linking of peptidoglycans, providing structural integrity to the bacterial cell wall.
Elimination Pathways: Primarily renal excretion with some hepatic metabolism.
Dosage
Standard Dosage
Adults:
- Mild to moderate infections: 250-500 mg every 6 hours.
- Severe infections: Up to 1000 mg every 6 hours.
Children:
- Dosage based on weight: 25-50 mg/kg/day, divided into four doses.
Special Cases:
- Elderly Patients: Standard adult dosing. Monitor renal function.
- Patients with Renal Impairment: Dose adjustment is necessary based on the degree of impairment.
- Patients with Hepatic Dysfunction: Use with caution and monitor hepatic function. Dose adjustments may be required.
- Patients with Comorbid Conditions: Consider disease-specific interactions and potential complications.
Clinical Use Cases
Dosage and duration are adjusted based on the specific infection being treated. Generally, continue treatment for the prescribed duration, even if symptoms improve.
Dosage Adjustments
- Renal dysfunction: Reduce the dose or prolong the dosing interval based on creatinine clearance or glomerular filtration rate.
- Hepatic dysfunction: Use with caution, monitor liver function, and consider dose adjustments.
Side Effects
Common Side Effects:
- Nausea, vomiting, diarrhea
- Abdominal pain
- Heartburn
- Headache
- Rash
- Mouth sores
Rare but Serious Side Effects:
- Clostridium difficile infection (CDI)
- Allergic reactions (ranging from mild skin rashes to anaphylaxis)
Long-Term Effects: None typically reported.
Adverse Drug Reactions (ADR):
- Anaphylaxis (rare but serious)
- Stevens-Johnson syndrome (rare but serious)
Contraindications
- Hypersensitivity to penicillins or cephalosporins
- History of severe allergic reaction to any beta-lactam antibiotic
Drug Interactions
- Probenecid: Increases and prolongs penicillin serum concentrations.
- Anticoagulants (e.g., warfarin): Dicloxacillin may reduce the anticoagulant effect. Monitor prothrombin time/INR.
- Methotrexate: Penicillins may reduce its clearance, leading to toxicity.
- Allopurinol: May increase the risk of skin rash.
- Oral contraceptives: Effectiveness may be decreased. Advise patients to use alternative methods of contraception.
Pregnancy and Breastfeeding
- Pregnancy: Pregnancy category B. Considered safe, but use with caution and only if clearly needed.
- Breastfeeding: Small amounts are excreted in breast milk. Monitor infant for diarrhea or thrush.
Drug Profile Summary
- Mechanism of Action: Inhibits bacterial cell wall synthesis by binding to PBPs.
- Side Effects: Nausea, vomiting, diarrhea, rash, allergic reactions.
- Contraindications: Hypersensitivity to penicillins or cephalosporins.
- Drug Interactions: Probenecid, anticoagulants, methotrexate, allopurinol.
- Pregnancy & Breastfeeding: Generally safe, use with caution.
- Dosage: Adult: 250-1000 mg every 6 hours; Pediatric: 25-50 mg/kg/day divided into four doses.
- Monitoring Parameters: Renal and hepatic function (with prolonged use), observe for signs of allergy.
Popular Combinations
Amoxycillin is sometimes combined with clavulanate (a beta-lactamase inhibitor) to extend its spectrum of activity against beta-lactamase-producing bacteria. While dicloxacillin itself offers this advantage, the combination with amoxycillin offers broader coverage than dicloxacillin alone. It is important to note that a combination of amoxicillin, dicloxacillin, and lactobacillus is also available. Lactobacillus is a probiotic added to reduce the risk of antibiotic-associated diarrhea.
Precautions
- General Precautions: Evaluate for penicillin allergy. Monitor for adverse reactions.
- Specific Populations: Close monitoring in patients with renal or hepatic impairment.
- Lifestyle Considerations: Avoid alcohol during treatment as it may exacerbate side effects.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Amoxycillin + Dicloxacillin?
A: Adults: 250-1000 mg every 6 hours, depending on the severity of the infection. Pediatrics: 25-50 mg/kg/day, divided into four doses. Adjust for renal or hepatic impairment.
Q2: What are the most common side effects?
A: Gastrointestinal upset (nausea, vomiting, diarrhea), rash, mouth sores.
Q3: What are the contraindications?
A: Hypersensitivity to penicillins or cephalosporins.
Q4: How does this combination work against resistant bacteria?
A: Dicloxacillin is resistant to breakdown by beta-lactamases, extending the effectiveness of the combination against these bacteria.
Q5: Can Amoxycillin + Dicloxacillin be used in pregnancy?
A: Pregnancy category B. Use cautiously and only if clearly needed.
Q6: Can it be used during breastfeeding?
A: Small amounts are present in breast milk. Monitor the infant for adverse effects like diarrhea or thrush.
Q7: What are the potential drug interactions?
A: Probenecid, anticoagulants (e.g., warfarin), methotrexate, and allopurinol.
Q8: What if a patient has renal impairment?
A: Dosage adjustment is necessary, depending on the severity of impairment. Consult renal dosing guidelines.
Q9: Can this medication be used for viral infections?
A: No, it is not effective against viral infections.
Q10: What should be done in case of an allergic reaction?
A: Discontinue the medication immediately and provide appropriate medical care (antihistamines, corticosteroids, epinephrine, as needed).
