Roxithromycin

BRAND NAMES

Roxithromycin is marketed under several brand names worldwide. The most commonly known brand is Rulid, which is available in tablet form. Other brands include Roxit, Roximycin, Rulide, and Roxim. Brand names may vary by country and formulation. These brands make it easier for patients and prescribers to identify the medication.

MECHANISM OF ACTION

Roxithromycin works by binding to the 50S ribosomal subunit of susceptible bacteria. This inhibits protein synthesis, preventing bacterial growth and replication. It acts primarily as a bacteriostatic agent, although high concentrations may be bactericidal. Its mechanism targets Gram-positive bacteria and some Gram-negative strains. This dual activity makes it effective in respiratory, skin, and soft tissue infections.

PHARMACOKINETICS:

Absorption

Roxithromycin is rapidly absorbed after oral administration. Peak plasma concentrations occur within 1–2 hours. Taking it with food can enhance absorption slightly. Its bioavailability is high, allowing effective systemic concentrations. The absorption rate supports once- or twice-daily dosing.

Distribution                

The drug distributes widely into body tissues, including lungs, tonsils, and sinuses. Low plasma protein binding allows greater free drug availability. Tissue concentrations often exceed plasma levels, enhancing efficacy. Roxithromycin crosses the placenta but minimally enters cerebrospinal fluid. Distribution is consistent in most adult populations.

Metabolism

Roxithromycin undergoes partial metabolism in the liver through demethylation and oxidation. Minor metabolites have little antibacterial activity. Metabolism is not heavily dependent on CYP450 enzymes, reducing drug interactions. Liver function can influence the rate of metabolism. The drug maintains effective plasma levels for once- or twice-daily dosing.

Excretion

Roxithromycin is primarily excreted in bile and feces, with minimal renal excretion. The half-life supports convenient dosing schedules. Clearance may be slower in patients with hepatic impairment. Less than 10% of the drug is excreted unchanged in urine. This excretion profile minimizes accumulation in patients with normal liver function.

PHARMACODYNAMICS

Roxithromycin exerts bacteriostatic effects by inhibiting bacterial protein synthesis. Its activity is concentration-dependent and time-dependent, requiring consistent dosing. Effective against Gram-positive bacteria and selected Gram-negative species. It reduces bacterial load and indirectly decreases inflammation. Its clinical use focuses on respiratory, skin, and soft tissue infections.

ADMINISTRATION

Roxithromycin is administered orally, either as tablets or suspension. It can be taken with or without food for convenience. The standard dosing frequency is once or twice daily depending on infection severity. Patients are advised to complete the full course to prevent resistance. Adjustments may be necessary in hepatic impairment.

DOSAGE AND STRENGTH

Typical adult doses range from 150–300 mg twice daily depending on the infection. Pediatric dosing is weight-based, usually 5–8 mg/kg/day. Tablets are available in 150 mg and 300 mg strengths. Oral suspension is commonly 50 mg/5 mL. Treatment duration generally ranges from 7–10 days, depending on the infection type.

DRUG INTERACTIONS

Roxithromycin may interact with warfarin, theophylline, and cyclosporine. Caution is advised with other CYP3A4-metabolized drugs. Co-administration with other macrolides may increase the risk of side effects. Monitoring is recommended for drugs that prolong QT interval. Always check for interactions before starting therapy.

FOOD INTERACTIONS

Food slightly enhances absorption but is not critical for effectiveness. Fatty meals may delay peak plasma concentrations. No strict dietary restrictions are necessary. Alcohol does not significantly affect pharmacokinetics. Hydration can reduce gastrointestinal discomfort during therapy.

CONTRAINDICATIONS

Roxithromycin is contraindicated in patients with hypersensitivity to macrolides or erythromycin. Patients with a history of cholestatic jaundice from macrolides should avoid it. Severe hepatic impairment warrants caution or dose adjustment. Pre-existing QT prolongation is a concern. Avoid use in patients with known allergy to any formulation of Roxithromycin.

SIDE EFFECTS

• Nausea, vomiting, and diarrhea

• Abdominal cramps and discomfort

• Headache or dizziness

• Skin rash or allergic reactions

• Rare liver enzyme elevation or jaundice

OVER DOSE

Excessive ingestion may lead to gastrointestinal symptoms like nausea, vomiting, and diarrhea. Severe cases can cause bradycardia or hypotension. Supportive treatment is recommended. Liver and kidney function should be monitored. No specific antidote exists; management is symptomatic.

TOXICITY

Roxithromycin toxicity is usually dose-dependent and reversible. High doses may cause hepatotoxicity or liver enzyme elevation. Prolonged QT interval may occur in predisposed individuals. Allergic reactions are rare but possible. Proper dosing and monitoring minimize serious adverse events.