Phenylephrine

 

1. Generic Name & Brand Names

• Generic Name: Phenylephrine HCl

• Common Brands:

  • Sudafed PE® (oral)

  • Neo-Synephrine® (nasal)

  • 4-Way Fast Acting® (nasal spray)

  • Multi-symptom cold products (e.g., DayQuil Severe®, Theraflu ExpressMax®)

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2. Dosage Forms

• Nasal:

  • Sprays (0.25%, 0.5%, 1%)

  • Drops (0.125% pediatric)

• Oral:

  • Tablets (5 mg, 10 mg)

  • Liquid suspensions (2.5 mg/5mL)

• Ophthalmic: Eye drops (2.5%, 10%)

• Injectable: IV (hospital use)

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3. Drug Class

• α₁-Adrenergic Agonist

• Direct-acting sympathomimetic

• Vasoconstrictor/decongestant

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4. Uses

• Nasal Congestion Relief:

  • Common cold, allergies, sinusitis

• Ophthalmic:

  • Pupil dilation during eye exams

  • Ocular redness relief (lower concentrations)

• Medical Emergencies:

  • IV form for shock/hypotension (ICU setting)

• Off-label: Priapism treatment

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5. Side Effects

Common (>5%)	Serious (Require Discontinuation)
Rebound congestion	Severe hypertension
Headache	Cardiac arrhythmias
Nose burning (spray)	Cerebral hemorrhage
Insomnia (oral)	Acute kidney injury
Palpitations (oral)	Angle-closure glaucoma

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6. Critical Warnings

• FDA Efficacy Alert (2023):

  Oral phenylephrine ineffective at standard doses due to extensive first-pass metabolism (<1% bioavailability)

• Contraindications:

  • Severe hypertension/Coronary artery disease

  • MAOI use within 14 days

  • Narrow-angle glaucoma

• Rebound Rhinitis:

  Nasal sprays cause rhinitis medicamentosa if used >3 consecutive days

• High-Risk Groups:

  • Hyperthyroidism, BPH, diabetes

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7. How to Use

Form	Adults	Duration Limit
Nasal Spray	2-3 sprays/nostril 0.5% sol (q4h)	≤3 days
Nasal Drops	2-4 drops/nostril 0.25% (q4h)	≤3 days
Oral Tablets	10 mg q4h (max 60 mg/day)	≤7 days

• Proper Nasal Technique:

  1. Blow nose gently

  2. Tilt head slightly forward

  3. Insert nozzle away from nasal septum

  4. Spray laterally while breathing gently

  5. Avoid deep inhalation

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8. Pediatric Use

Age	Nasal Drops	Oral Liquid
6-12 years	0.25%: 2-3 drops	5 mg q4h
2-5 years	0.125%: 2-3 drops	Avoid oral
<2 years	CONTRAINDICATED	CONTRAINDICATED

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9. Efficacy Controversy

• Oral Phenylephrine:

  • Systematic reviews show no better than placebo for congestion relief

  • FDA advisory panel voted 16-0 (Sept 2023) to remove OTC status

• Effective Alternatives:

  • Nasal corticosteroids: Fluticasone (Flonase®)

  • Oral decongestants: Pseudoephedrine (behind-counter)

  • Saline irrigation: Neti pot with distilled water

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10. Overdose

• Symptoms:

  Hypertension, reflex bradycardia, seizures, pulmonary edema

• Management:

  • IV phentolamine (α-blocker)

  • Benzodiazepines for seizures

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11. Drug Interactions

Medication	Risk
MAO Inhibitors	Hypertensive crisis (fatal)
Beta-Blockers	Unopposed α-stimulation → severe HTN
Stimulants	Additive cardiovascular effects

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12. Storage

• Nasal Sprays:

  • Store upright at 15-30°C (59-86°F)

  • Discard 3 months after opening

• Oral Forms:

  • Protect from moisture

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Critical Safety Alerts

⚠️ Rebound Congestion Risk:

"Nasal spray addiction" develops in 50% of users after 3 days - strictly limit use duration
⚠️ Oral Inefficacy:
Avoid oral phenylephrine - proven ineffective per FDA review
⚠️ Hypertensive Crisis:
Monitor BP in vulnerable patients - even topical absorption can spike BP

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Phenylephrine vs. Pseudoephedrine

Parameter	Phenylephrine (Oral)	Pseudoephedrine
Bioavailability	<1%	90-100%
Efficacy	Ineffective	High
OTC Access	Shelf	Behind-counter (ID)
Abuse Potential	Low	High (meth precursor)
Duration	4 hours	6-12 hours

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Clinical Recommendations

✅ Effective Use:

• Nasal spray: For severe acute congestion ≤3 days

• Eye drops: For ocular procedures
  ❌ Avoid:

• Oral formulations for congestion

• Any form in infants/toddlers

• Prolonged nasal use (>72 hours)
  💡 Pro Tip:

Combine nasal saline rinses with intranasal corticosteroids (e.g., mometasone) for allergic congestion

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📊 Evidence Update:

• JAMA study (2023): 10mg oral phenylephrine showed zero significant improvement vs. placebo in 539 adults.

• Cochrane Review: Nasal sprays provide relief but with rebound risk after 3 days.

Regulatory Status: FDA review ongoing; may be removed from OTC market in 2024.