What prescription should I write for a 16‑year‑old (~60 kg) patient with severe nodular acne, including isotretinoin dosing, baseline labs, topical regimen, intralesional triamcinolone for large nodules, and alternatives if isotretinoin is contraindicated?

Prescription for Severe Nodular Acne in a 16-Year-Old (~60 kg) Patient

Begin isotretinoin at 30 mg daily (0.5 mg/kg/day) with food for the first month, then escalate to 60 mg daily (1.0 mg/kg/day) divided into two doses with meals, targeting a cumulative dose of 7,200–9,000 mg over 15–20 weeks to minimize relapse. 1

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Isotretinoin Prescription Details

Initial Month Dosing

• Start with isotretinoin 30 mg once daily with a meal for the first 4 weeks to allow tolerance assessment and minimize initial inflammatory flare risk. 1, 2
• For a 60 kg patient, this represents the recommended 0.5 mg/kg/day starting dose. 1

Maintenance Dosing (Month 2 Onward)

• Escalate to isotretinoin 60 mg daily (30 mg twice daily with meals) if the initial month is well-tolerated. 1, 2
• This 1.0 mg/kg/day maintenance dose achieves the target cumulative exposure of 120–150 mg/kg (7,200–9,000 mg total for 60 kg) within the standard 15–20 week treatment course. 1
• Taking isotretinoin with meals is mandatory because it is highly lipophilic; absorption without food is significantly reduced. 1, 2

Treatment Duration

• Continue therapy for at least 2 months after achieving complete clearance to reduce relapse frequency. 1
• Most patients require 15–20 weeks total, though 15% may need up to 10 months if response is slow. 3

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Baseline Laboratory Testing (Before First Dose)

Obtain these three mandatory tests: 1

1. Liver function tests (AST, ALT) – abnormal values occur in 0.8–10.4% of patients. 1
2. Fasting lipid panel (triglycerides, total cholesterol, LDL, HDL) – elevated triglycerides occur in 7.1–39.0% and abnormal cholesterol in 6.8–27.2%. 1
3. Pregnancy test (urine or serum β-hCG) for all females with childbearing potential. 1

CBC is not required in otherwise healthy adolescents receiving isotretinoin. 1

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Monthly Monitoring Requirements

• Repeat liver function tests and fasting lipid panel monthly throughout treatment. 1
• Repeat pregnancy test monthly before each refill for females of childbearing potential. 1
• Screen for mood changes, depression, or anxiety at each visit using PHQ-2 or PHQ-9, though population-based studies show no increased neuropsychiatric risk (pooled RR 0.88,95% CI 0.77–1.00). 1, 2

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iPLEDGE Program Requirements

For Female Patients

• Mandate two concurrent forms of contraception starting 1 month before isotretinoin, continuing throughout treatment, and for 1 month after discontinuation. 1
• Monthly negative pregnancy tests are required before each prescription refill. 1

For Male Patients

• No contraception requirement, though counseling about the iPLEDGE program is necessary. 1

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Topical Regimen (Adjunctive Therapy)

Tretinoin 0.025% or 0.05% Cream

• Apply a thin layer once nightly to affected areas, avoiding eyes, mouth, nasal creases, and mucous membranes. 4
• Use with meals (for isotretinoin) and apply tretinoin at bedtime to separate administration and minimize irritation. 4
• Expected side effects include dryness, peeling, erythema, and burning—these are normal pharmacologic effects that typically subside within 2–4 weeks. 4
• Reduce application frequency to 2–3 times weekly if irritation is excessive, and recommend liberal emollient use. 4
• Avoid sun exposure and mandate daily broad-spectrum sunscreen (SPF ≥30) and protective clothing, as both isotretinoin and tretinoin increase photosensitivity. 4

Benzoyl Peroxide 2.5% or 5% Gel

• Apply once daily in the morning to complement tretinoin's comedolytic action and prevent bacterial resistance. 4
• Fixed-dose combinations (adapalene/benzoyl peroxide) are strongly recommended by the American Academy of Dermatology for multimodal therapy. 4

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Intralesional Triamcinolone for Large Nodules

• Inject triamcinolone acetonide 2.5–5 mg/mL (0.1–0.3 mL per nodule) directly into large, painful nodules to rapidly reduce inflammation and prevent scarring. 1
• Limit injections to 2–3 nodules per visit to minimize systemic corticosteroid absorption and local atrophy risk. 1
• This adjunctive measure is particularly useful during the first 4–8 weeks while isotretinoin takes effect. 1

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Alternatives If Isotretinoin Is Contraindicated

Combination Therapy (Non-Isotretinoin)

If isotretinoin is contraindicated (e.g., pregnancy, refusal to comply with iPLEDGE, severe hypertriglyceridemia), prescribe: 5

1. Doxycycline 100 mg twice daily (or minocycline 100 mg twice daily). 5
2. Adapalene 0.1%/benzoyl peroxide 2.5% gel once nightly. 5
3. Continue for at least 20 weeks, as this regimen showed noninferiority to isotretinoin in the per-protocol population (74.3% vs. 58% composite efficacy/safety endpoint, 95% CI 3.9–28.6, P = 0.01). 5

This combination has half the rate of medically relevant adverse events compared to isotretinoin (18.0% vs. 33.8%) and shows significantly earlier onset of action at week 2. 5

Low-Dose Isotretinoin (If Standard Dose Not Tolerated)

• Consider isotretinoin 0.25–0.4 mg/kg/day (15–25 mg daily for 60 kg) for more than 6 months if standard dosing causes intolerable side effects. 1, 6
• This regimen provides comparable efficacy with markedly reduced mucocutaneous side effects, though treatment duration must be extended to achieve adequate cumulative exposure. 1, 6

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Common Pitfalls and How to Avoid Them

• Do not prescribe intermittent dosing (e.g., 1 week per month)—this significantly increases relapse rates compared to continuous daily dosing. 1, 2
• Do not stop isotretinoin immediately upon clearance—continue for 2 additional months to reduce relapse risk. 1
• Do not combine isotretinoin with tetracyclines (doxycycline, minocycline)—this increases pseudotumor cerebri risk. 1
• Do not allow patients to take isotretinoin without food—bioavailability drops significantly. 1, 2
• Do not perform chemical peels within 6 months of isotretinoin completion—risk of abnormal scarring and delayed wound healing. 4

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Side Effect Management

• Mucocutaneous dryness (lips, eyes, skin): Recommend liberal emollient use, ocular lubricants, and lip balm. 1
• Elevated triglycerides: Consider omega-3 supplementation (1 g/day) and dietary modification; discontinue if triglycerides exceed 500–800 mg/dL. 1
• Myalgias (up to 25% on high-dose): Reassure that these do not affect muscle strength; consider dose reduction if severe. 1
• Initial acne flare: If extremely severe (acne fulminans), start isotretinoin at 0.1–0.3 mg/kg/day with oral prednisone 0.5–1 mg/kg/day, then taper corticosteroids as isotretinoin is escalated. 1, 2

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Relapse Risk Factors

• Age <16 years: Approximately 25% higher relapse risk—consider cumulative doses ≥220 mg/kg from the outset. 1
• Truncal acne and male sex: Higher relapse rates—ensure cumulative dose reaches 120–150 mg/kg minimum. 3
• Cumulative dose <120 mg/kg: Significantly higher relapse rates—do not underdose. 1, 3