Cisapride
Contraindicated
Database
Possible rise in plasma levels of cisapride.
Exercise caution.
Drug reference
roxithromycin
Semisynthetic 14-membered macrolide antibiotic · Antibacterial
START
150 mg PO twice daily before food for 5–10 days
TYPICAL MAX
300 mg/day
STOP IF
Hepatitis, severe rash, or significant QT prolongation
WATCH
LFTs, ECG if QT-drug co-use, GI tolerance
CDSCO approvedATC J01FA06
KDIGO 2024 + manufacturer label
- ONSET
- 1h · absorption
- PEAK
- 2h · Tmax
- t½
- 12h · t½
- DURATION
- 12h · twice-daily
EXCRETION
Mainly faecal; minor renal
route + CYP
INTERACTIONS
5 major
incl. contraindicated
PREGNANCY
Use only if clearly needed; macrolide class generally acceptable.
FDA category + note
Top interactionssee all 12 →
- CisaprideContraindicatedDatabase
- ErgotamineContraindicatedDatabase
- PimozideContraindicatedDatabase
- Ergot AlkaloidsContraindicatedDatabaseKimi deep-research + Cla
Mechanism
Binds the bacterial 50S ribosomal subunit, inhibiting protein synthesis; bacteriostatic against Gram-positive cocci, atypicals (Mycoplasma, Chlamydia, Legionella) and some Gram-negatives.
Indications
Respiratory tract infections (pharyngitis, tonsillitis, bronchitis, pneumonia)Skin / soft-tissue infectionsGenital infections (Chlamydia, non-gonococcal urethritis)
Dosing
- Adult
- 150 mg PO twice daily OR 300 mg once daily for 5–10 days; take 15 min before food.
- Pediatric
- 5–8 mg/kg/day in 1–2 divided doses.
- Renal adjustment
- Caution in severe impairment; usually no fixed adjustment.
- Hepatic adjustment
- Reduce dose / extend interval in significant hepatic impairment.
- Geriatric
- Standard; monitor.
- Max dose
- 300 mg/day
Pharmacokinetics
Onset
Antibacterial effect over hours
Peak effect
~2 h (Tmax)
Duration
~12 h (twice-daily)
Half-life
~12 h
Bioavailability
~50% (better fasting)
Protein binding
~96%
Metabolism
Minimal hepatic
Excretion
Mainly faecal; minor renal
Contraindications
- Macrolide hypersensitivity
- Concomitant ergot alkaloids
- Caution: QT prolongation, hepatic impairment
Side effects
Common
Nausea/vomitingAbdominal painDiarrhoeaHeadacheRash
Serious
- QT prolongation (less than erythromycin/clarithromycin)
- Hepatotoxicity (cholestatic)
- Severe hypersensitivity / SJS
- C. difficile colitis
Pregnancy & lactation
Pregnancy
Use only if clearly needed; macrolide class generally acceptable.
Lactation
Small amounts in milk; generally compatible.
Drug interactions
Ergotamine
Contraindicated
Database
Increased plasma concentrations of ergotamine, leading to ergotism (vasospasm, ischemia of extremities and other tissues).
Concomitant use is contraindicated due to the risk of severe and potentially life-threatening vasospasm. Avoid completely.
Pimozide
Contraindicated
Database
Increased pimozide levels, leading to QT prolongation and potentially fatal ventricular arrhythmias (e.g., Torsades de Pointes).
Concomitant use is contraindicated. Avoid completely.
Ergot Alkaloids
Contraindicated
Database
Reduced ergot metabolism
Contraindicated
Source: Kimi deep-research + Cla
Colchicine
Severe
Database
Colchicine toxicity (gastrointestinal symptoms, myelosuppression, rhabdomyolysis, neuropathy).
Avoid concomitant use. If unavoidable, significantly reduce colchicine dose and monitor closely for toxicity.
Terfenadine
Moderate
Textbook
Possible rise in plasma levels of terfenadine.
Exercise caution.
Source: KDT 7e · p754
Amiodarone
Moderate
Database
Increased risk of ventricular arrhythmias, including Torsades de Pointes.
Avoid concomitant use in patients with risk factors for QT prolongation (e.g., hypokalemia, bradycardia, pre-existing heart disease). If co-administration is necessary, monitor ECG and electrolytes. Consider alternative antibiotics.
Bromocriptine
Moderate
Database
Increased bromocriptine levels, leading to increased risk of adverse effects (e.g., nausea, vomiting, hypotension, hallucinations).
Monitor for increased adverse effects of bromocriptine. Consider reducing bromocriptine dose.
Carbamazepine
Moderate
Database
Increased carbamazepine levels, leading to increased risk of toxicity (e.g., dizziness, ataxia, diplopia, nausea, vomiting).
Monitor carbamazepine levels and clinical signs of toxicity. Reduce carbamazepine dose if necessary.
Ciclosporin
Moderate
Database
Increased risk of ciclosporin toxicity (nephrotoxicity, neurotoxicity, hepatotoxicity).
Monitor ciclosporin trough levels closely. Adjust ciclosporin dose as needed.
Cyclosporine
Moderate
Database
Increased cyclosporine levels, leading to increased risk of nephrotoxicity and other adverse effects.
Monitor cyclosporine levels closely. Reduce cyclosporine dose as needed. Monitor renal function.
Digoxin
Moderate
Database
Increased digoxin levels and potential for digoxin toxicity (nausea, vomiting, arrhythmias).
Monitor digoxin levels and clinical signs of toxicity. Reduce digoxin dose if necessary. Consider alternative antibiotics if possible.
Related guidelines
Ask House about roxithromycin
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e·Verified: 2026-05-20 · House clinical team·Cockpit curated: 2026-05-20