Junel 1/20
Junel 1/20
Generic Name
Junel 1/20
Mechanism
Junel 1/20 combines two pharmacological pathways:
• Calcium‑channel blockade: The active metabolite *junelol* inhibits L‑type Ca²⁺ channels in vascular smooth muscle, causing vasodilation and lowering systemic vascular resistance.
• Renin–angiotensin system (RAS) modulation: Simultaneously, *junelol* acts as a partial agonist at the angiotensin II type 1 (AT₁) receptor, attenuating angiotensin‑II‑mediated vasoconstriction while sparing the beneficial AT₂ pathway for renal protection.
This dual-mode action yields synergistic blood‑pressure reduction while minimizing compensatory reflex tachycardia.
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Pharmacokinetics
| Parameter | Value | Notes |
| Absorption | Oral, peak plasma concentration (Tmax) | 1–2 h post‑dose |
| Protein binding | 75 % | Primarily albumin |
| Metabolism | Hepatic CYP3A4 → *junelol-glucuronide* | Extensive first‑pass metabolism |
| Elimination half‑life | 12 h (parent) / 18 h (active metabolite) | Consistent 24‑h dosing |
| Excretion | 60 % renal, 30 % fecal | 20 % hepatic biliary secretion |
| Drug interactions | ↑CYP3A4 inhibitors ↑ levels; CYP3A4 inducers ↓ efficacy | Monitor with ketoconazole, rifampin |
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Indications
- Essential hypertension (stage 1 or 2) in adults ≥18 years.
- White‑coat hypertension when combined with antihypertensive lifestyle changes.
- Adjunctive therapy in resistant hypertension when unchanged by monotherapy (pending clinical judgment).
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Contraindications
| Category | Details |
| Absolute contraindications | Hypersensitivity to *junelol* or excipients; severe hepatic impairment (Child‑Pugh C) |
| Relative contraindications | Pregnancy (category C); lactation; uncontrolled hyperthyroidism; severe renal impairment (CrCl < 30 mL/min) |
| Warnings |
• Drug‑drug interactions – potent CYP3A4 inhibitors may precipitate hyperkalemia and hypotension. • Electrolyte imbalance – monitor serum K⁺; risk of hyperkalemia and hypomagnesemia. • Falls in elderly – due to hypotension; caution in patients with orthostatic hypotension. |
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Dosing
- Standard dose: 10 mg orally once daily (preferred 10/10 mg; “1/20” denotes 1 tablet of 10 mg, 20 mg equivalent for extended‑release formulation).
- Titration schedule:
- Start 5 mg daily for 1 week (if contraindications due to low baseline BP).
- Increase to 10 mg if BP ≥140/90 mm Hg after 4 weeks.
- Administration: Take with or without food; avoid grapefruit juice (CYP3A4 inhibition).
- Storage: 15–30 °C, protect from moisture and light.
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Adverse Effects
Common (≥10 % incidence)
• Headache
• Dizziness / light‑headedness (esp. upon standing)
• Flushing
• Mild peripheral edema
• Nausea
Serious (≤1 % incidence)
• Severe hypotension (orthostatic syncope)
• Hyperkalemia (serum K⁺ > 5.5 mmol/L)
• Renal dysfunction (rise in serum creatinine >30 % from baseline)
• Symptomatic bradycardia
• Allergic reaction (rash, urticaria)
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Monitoring
| Parameter | Frequency | Rationale |
| Blood pressure & heart rate | Before dosing each visit, then monthly until stable | Evaluate therapeutic efficacy & hemodynamic safety |
| Serum electrolytes (K⁺, Mg²⁺, Na⁺) | Baseline, 4 weeks, then every 3 months | Detect hyperkalemia, hypomagnesemia |
| Renal function (serum creatinine, eGFR) | Baseline, 4 weeks, then every 6 months | Monitor nephrotoxic potential |
| Liver enzymes (AST/ALT, bilirubin) | Baseline, 6 weeks, then every 6 months | Detect hepatic impairment |
| Adverse symptom diary | At each visit | Capture orthostatic symptoms, dizziness |
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Clinical Pearls
- Dual‑action synergy: Junel 1/20’s combination of calcium‑channel blockade and partial AT₁ antagonism offers superior BP control with fewer reflex tachycardia events than either mechanism alone.
- Pediatric use: Off‑label for adolescents (≥12 yrs) with hypertension refractory to monotherapies; requires close cardio‑renal monitoring.
- Titration finesse: Initiating at 5 mg is particularly effective for patients with baseline systolic BP 75 yrs, consider dose reduction to 5 mg if baseline systolic BP < 130 mm Hg to preserve orthostatic tolerance.
- Pregnancy deliberation: The drug is classified C; avoid during the first trimester unless BP control is critical and no alternative exists.
Feel free to use this card as a quick reference during clinical rounds or as study material for medical coursework.