Usage
- This combination is prescribed for various bacterial infections, including acne, pneumonia, bronchitis, urinary tract infections (UTIs), Q fever, brucellosis, psittacosis, eye infections, some sexually transmitted infections (STIs) like gonorrhea, syphilis, and chlamydia, and malaria (when chloroquine is ineffective). Lactobacillus is added to help prevent antibiotic-associated diarrhea caused by Doxycycline.
- Pharmacological Classification: Doxycycline is a tetracycline antibiotic, and Lactobacillus is a probiotic.
- Mechanism of Action: Doxycycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, thus preventing bacterial growth and spread. Lactobacillus helps restore the gut microbiota and produces lactic acid, creating an acidic environment that inhibits the growth of harmful bacteria.
Alternate Names
Doxycycline is also known as Vibramycin, Oracea, Adoxa, Monodox, and Doxycin. Lactobacillus may appear in combination products under specific strain names (e.g., Lactobacillus acidophilus, Lactobacillus rhamnosus). There aren’t standard international variations for this combination product as it’s not a unified medication, but rather co-administration of two different agents. Brand names for combination products containing both ingredients may vary regionally. Eldidox 100, for example, is one such brand name.
How It Works
- Pharmacodynamics: Doxycycline exerts its bacteriostatic effect by inhibiting protein synthesis. Lactobacillus promotes a healthy gut microbiome and aids in digestion.
- Pharmacokinetics: Doxycycline is well-absorbed orally and reaches peak serum concentrations in 2-3 hours. It’s metabolized in the liver and excreted primarily in the feces. Lactobacillus, being a live organism, colonizes the gut.
- Mode of Action: Doxycycline binds to the 30S ribosomal subunit in bacteria, preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex, ultimately inhibiting protein synthesis. Lactobacillus adheres to the intestinal mucosa, produces lactic acid, and competes with pathogenic bacteria for resources.
- Elimination Pathways: Doxycycline is primarily excreted in feces via biliary excretion; some renal excretion occurs as well.
Dosage
Standard Dosage
Adults:
- Doxycycline: Initial dose of 200 mg on the first day (100 mg every 12 hours), followed by a maintenance dose of 100 mg daily or 100 mg every 12 hours for more severe infections. Duration of treatment typically ranges from 7 to 10 days but can extend up to 30 days for certain indications.
- Lactobacillus: Dosage varies with specific strains. Typical doses range from 1 billion to 10 billion colony-forming units (CFU) daily. One brand name (Eldidox) contains 90 million spores.
Children:
- Doxycycline is generally avoided in children under 8 years of age due to the risk of tooth discoloration. For children over 8 years and weighing 45 kg or less, the dosage is 2.2 mg/kg every 12 hours. For children weighing more than 45 kg, the adult dose applies. Lactobacillus dosing in children also varies by strain and formulation.
Special Cases:
- Elderly Patients: Dosage adjustments are usually not required, but careful monitoring for adverse effects is advised.
- Patients with Renal Impairment: Doxycycline dosage adjustment is generally not necessary in patients with renal impairment, since it does not require hepatic metabolism.
- Patients with Hepatic Dysfunction: Dosage adjustment may be considered in severe hepatic impairment due to potentially delayed biliary excretion.
- Patients with Comorbid Conditions: Caution is advised for patients with conditions such as diabetes, cardiovascular disease, or other chronic illnesses, and adjustments may be needed.
Clinical Use Cases Clinical use cases for Doxycycline include various infectious diseases, while Lactobacillus is utilized for its probiotic effects, primarily for prevention or treatment of antibiotic associated diarrhea in this context. Dosage adjustments in these scenarios should be tailored to the specific infection and patient characteristics.
- Intubation, Surgical Procedures, Mechanical Ventilation, Intensive Care Unit (ICU) Use, Emergency Situations: Doxycycline + Lactobacillus administration in these cases depends on the underlying infection being treated. Standard dosing guidelines, with modifications based on individual patient factors, are applicable. The combination isn’t specifically indicated for these clinical situations themselves.
Dosage Adjustments
Dose modifications should be made for patients with severe hepatic impairment. Drug interactions may necessitate adjustments. Genetic factors influencing drug metabolism may require consideration.
Side Effects
Common Side Effects
- Nausea, vomiting, diarrhea, indigestion
Rare but Serious Side Effects
- Clostridium difficile infection, severe allergic reactions, intracranial hypertension, hepatotoxicity
Long-Term Effects
- Tooth discoloration, photosensitivity
Adverse Drug Reactions (ADR)
- Angioedema, anaphylaxis, Stevens-Johnson syndrome
Contraindications
- Hypersensitivity to tetracycline antibiotics or any component of the formulation
- Pregnancy (especially second and third trimesters)
- Breastfeeding
- Children under 8 years of age (unless absolutely necessary)
Drug Interactions
- Antacids containing aluminum, calcium, or magnesium, bismuth subsalicylate: reduced absorption of doxycycline
- Warfarin: enhanced anticoagulant effect
- Barbiturates, phenytoin, carbamazepine: decreased doxycycline serum concentrations
- Oral contraceptives: decreased efficacy
Pregnancy and Breastfeeding
- Pregnancy Safety Category: D (contraindicated)
- Fetal risks: Tooth discoloration, skeletal growth retardation
- Drug excretion in breast milk: Yes.
- Neonatal side effects: Possible tooth discoloration and other effects observed in older children.
Drug Profile Summary
- Mechanism of Action: Doxycycline: inhibits bacterial protein synthesis; Lactobacillus: promotes healthy gut flora
- Side Effects: Nausea, vomiting, diarrhea; rare but serious side effects include C. difficile infection and allergic reactions
- Contraindications: Hypersensitivity, pregnancy, breastfeeding, children under 8
- Drug Interactions: Antacids, warfarin, anticonvulsants, oral contraceptives
- Pregnancy & Breastfeeding: Contraindicated
- Dosage: Doxycycline: Adults: 200 mg initially, followed by 100 mg daily or BID; children: consult guidelines; Lactobacillus: Varies by strain
- Monitoring Parameters: Signs and symptoms of infection, liver and kidney function tests, complete blood count
Popular Combinations
Doxycycline is sometimes combined with other antibiotics for specific infections. Doxycycline + Lactobacillus is specifically used to prevent or alleviate antibiotic-associated diarrhea. It is crucial to consult guidelines for appropriate combination therapies and monitor patients for adverse effects.
Precautions
- Evaluate for hypersensitivity to tetracyclines.
- Assess renal and hepatic function.
- Advise patients about photosensitivity and sun protection.
- Monitor for signs of C. difficile infection.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Doxycycline + Lactobacillus?
A: Doxycycline: 200 mg initially, then 100 mg daily or BID; Lactobacillus: varies based on the strain and formulation.
Q2: Can Doxycycline + Lactobacillus be used in pregnant or breastfeeding women?
A: No, it’s contraindicated in both pregnancy and breastfeeding.
Q3: What are the common side effects?
A: Nausea, vomiting, diarrhea, and indigestion are the common side effects.
Q4: How does Doxycycline interact with oral contraceptives?
A: Doxycycline may reduce the effectiveness of oral contraceptives.
Q5: What are the considerations for children under 8?
A: Avoid use due to the risk of permanent tooth discoloration.
Q6: What should patients be advised about regarding sun exposure?
A: Doxycycline can cause photosensitivity, so advise patients to use sun protection.
Q7: What are the signs of a C. difficile infection?
A: Watery diarrhea, abdominal pain, fever.
Q8: Should dose adjustments be made for renal dysfunction?
A: No, doxycycline dose adjustment isn’t usually necessary in renal impairment.
Q9: How long does Doxycycline stay in the system?
A: The half-life of Doxycycline is roughly 18-22 hours, meaning it can take several days for the drug to be mostly eliminated from the body. Traces may be detectable for longer periods.
Q10: Can patients consume dairy products while taking Doxycycline + Lactobacillus?
A: Dairy products, along with antacids containing calcium, can interfere with the absorption of doxycycline. It’s best to take doxycycline 1-2 hours before or 4-6 hours after consuming dairy or calcium-rich foods/supplements.
