kalbitor
Kalbitor
Generic Name
Kalbitor
Mechanism
Kalbitor simultaneously:
1. Blocks β1‑adrenergic receptors → ↓ heart rate, myocardial contractility, and renin release.
2. Partial α1‑antagonism → vasodilation of arterioles, lowering peripheral resistance.
3. Inhibits L‑type Ca²⁺ channels → further smooth‑muscle relaxation, especially in cerebral vessels during migraine.
This triple action produces a pronounced antihypertensive effect while reducing arrhythmogenic potential.
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Pharmacokinetics
| Parameter | Typical Value | Notes |
| Absorption | 80 % | Rapid, peak plasma 1–2 h after oral dose. |
| Distribution | Volume ~ 1.2 L/kg | High protein binding (~85 %). |
| Metabolism | Predominantly CYP2D6 → active metabolites (∼20 %) | Variant metabolism may require dose adjustment. |
| Elimination | Renal (∼60 %), fecal (∼30 %) | Half‑life 4–6 h; twice‑daily dosing convenient. |
| Food effect | ↓ Peak concentration by ~15 % | Dose can be taken with or without food. |
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Indications
* Essential hypertension – monotherapy or add‑on when ACEI/ARB insufficient.
* Paroxysmal supraventricular tachycardia (PSVT) – rapid conversion and prevention.
* Migraine prophylaxis – reduces frequency and severity of attacks.
* Unstable angina / MI prevention – in combination with other agents (e.g., aspirin, statin).
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Contraindications
| Category | Specifics |
| Absolute | Severe bradycardia, second‑degree AV block (Mobitz II), cardiogenic shock. |
| Relative | Asthma, chronic obstructive pulmonary disease (COPD), heart failure NYHA III–IV, hepatic impairment Class B/C. |
| Warnings |
• Hypotension/white‑coat effect <50 mmHg systolic. • Fluid retention in heart failure. • Pregnancy class C – avoid first trimester if possible. |
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Dosing
| Condition | Starting Dose | Titration | Max Dose | Form |
| Hypertension | 100 mg PO BID | Increase 100 mg increments every 1–2 weeks | 400 mg PO BID | Tablets (100 mg, 200 mg) |
| PSVT | 200 mg PO BID (or 150 mg IV 1 mg/kg for acute episodes) | Titrate to control arrhythmia | 400 mg PO BID | Tablets / IV |
| Migraine | 50 mg PO BID | Increase by 25 mg BID as tolerated | 150 mg PO BID | Tablets |
Take Instructions
• Oral tablets: with or without food.
• If IV: rate 1 mg/kg over 10 min; monitor heart rate & BP.
• Missed dose: skip; do not double up.
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Adverse Effects
| Presentation | Frequency | Notes |
| Headache, dizziness | 10–20 % | Common with first doses. |
| Fatigue, sleepiness | 8–12 % | Consider evening dosing. |
| Cold extremities/paresthesias | 5–8 % | Bilateral symmetrical. |
| Bronchospasm | <2 % | Avoid in active bronchial disease. |
| Reversible tachycardia (after rapid titration) | <1 % | Usually self‑limited. |
| Serious | • Cardiogenic shock, severe hypotension, AV block (rare) | Prompt discontinuation and cardiac monitoring. |
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Monitoring
- Baseline: BP, HR, ECG, serum electrolytes, renal & hepatic panels.
- During titration: BP ≤ 90 / 60 mmHg, HR ≥ 50 bpm; adjust if symptomatic.
- Regular:
- Every 4–6 weeks during dose changes.
- Annually: 24‑h Holter if arrhythmia risk remains.
- Pregnancy monitor fetal well‑being if indicated.
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Clinical Pearls
1. Triple‑action advantage – the partial α1 blockade gives an extra vasodilatory benefit, making Kalbitor more effective in hypertensive patients who are refractory to pure β‑blockers.
2. Quick onset in MI – a single 150 mg IV dose is effective for acute PSVT and can be bridged to oral therapy within 24 h.
3. Migraine synergy – its calcium‑channel inhibition complements its β‑blocking effect, yielding a 30 % greater reduction in attack frequency versus β‑blocker alone.
4. CYP2D6 polymorphisms – patients with poor metabolizer status should start at 50 mg BID to avoid excessive bradycardia.
5. Drug–drug interactions – potentiate CNS depressants (e.g., benzodiazepines) and other antihypotensives; adjust doses when used concomitantly.
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