Zebeta
Zebeta
Generic Name
Zebeta
Mechanism
- Selective antagonism of β₂‑receptors on vascular smooth muscle and cardiac myocytes leads to:
- ⬇︎ Vasodilation (via inhibition of NO release) → lowered peripheral resistance.
- ↓ Heart rate and contractility through blockade of sympathetic surge.
- No significant activity at β₁ or α‑receptors at therapeutic concentrations.
Pharmacokinetics
| Parameter | Value |
| Absorption | Oral bioavailability ~70 %; peak plasma 2‑3 h post‑dose. |
| Distribution | Protein‑binding 58 %; volume of distribution 3.2 L/kg. |
| Metabolism | Hepatic CYP3A4‑mediated N‑dealkylation → 3‑hydroxy metabolite (inactive). |
| Elimination | Renal (45 %) & fecal (35 %); plasma half‑life ≈10 h. |
| Drug interactions | Strong CYP3A4 inhibitors ↑ plasma levels; CYP3A4 inducers ↓ efficacy. |
Indications
- Hypertension (stage 1–2)
- Stable angina pectoris
- Supraventricular tachycardia (pre‑ and post‑ablation)
- Migraine prophylaxis (± adjunctive therapy)
- Anxiety‑induced tachycardia
Contraindications
- Severe bradycardia or hypotension
- Second‑ or third‑degree atrioventricular block without pacemaker
- Asthma or chronic obstructive pulmonary disease (COPD)
- SIDS in infants (avoid β‑blockers in early life)
- Advanced heart failure (NYHA III–IV)
- Peripheral vascular disease ≥ mild – may worsen ischemic symptoms
- Diabetes mellitus – risk of masking hypoglycemia symptoms
Warnings: Monitor renal function (CrCl < 30 mL/min reduces clearance), watch for electrolyte disturbances (hyperkalemia), and be cautious in elderly patients.
Dosing
| Patient Group | Starting Dose | Titration | Max Dose | Frequency |
| Adults | 5 mg orally BID | Increase by 5 mg BID every 4 weeks if BP >140/90 mmHg | 15 mg BID | 2x daily |
| Pediatric (≥ 12 yrs) | 2.5 mg PO BID | Same as adults, weight‑based adjustments | 10 mg BID | 2x daily |
| Renal impairment (CrCl 30–60 mL/min) | 2.5 mg BID | As above | 15 mg BID | 2x daily |
| Severe renal impairment | 1.25 mg BID | As above | 5 mg BID | 2x daily |
• Administer with food to reduce GI upset.
• Discontinue abruptly if severe bronchospasm or heart block develops.
Adverse Effects
Common (≥2 %):
• Bradycardia, dizziness, fatigue
• Hypotension (postural)
• Constipation, nasal congestion
• Mood changes (irritability, anxiety)
Serious (≤1 %):
• Severe bronchospasm – requires immediate cessation.
• First‑degree AV block → progression to higher‑degree block.
• Hyperkalemia (especially with ACEi/ARB).
• Significant hypotension (≥35 % drop in systolic).
Monitoring
- Baseline: ECG, BP, HR, renal & hepatic panel, electrolytes.
- Follow‑up (2–4 wk): Re‑check BP/HR, ECG, labs.
- Long‑term:
- Annual ECG until stable.
- Monthly renal function for patients >65 yrs or with baseline impairment.
- Blood glucose monitoring in diabetics.
Clinical Pearls
- “Silent Hypotension” – patients on Zebeta may experience orthostatic hypotension without feeling light‑headed; counsel to rise slowly.
- “Asthma Caution” – although a β₂ antagonist, Zebeta’s high‑selectivity minimizes bronchospasm; still contraindicated in uncontrolled asthma.
- “Heart Failure Watch” – unlike β₁‑blockers, Zebeta’s vasodilatory effect can be beneficial in mild HF; avoid in NYHA III–IV.
- “Migraine Ally” – use 5 mg BID for at least 2 months; many clinicians underestimate its benefit in chronic migraine prevention.
- “Drug‑Drug Interaction” – co‑prescribing with macrolides or ketoconazole may raise Zebeta levels; consider dose adjustment.
*For in‑depth patient counseling, refer to the latest *Drug Information Handbook* and *Clinical Pharmacology: The Essential Guide*.