Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ALA-SCALP vs ALPHADERM
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
ALA-SCALP (aminolevulinic acid) is a photosensitizer precursor that is converted intracellularly to protoporphyrin IX (Pp IX), which accumulates in cells with increased heme synthesis, such as rapidly dividing cells. Upon exposure to blue light (BLU-U®), Pp IX produces reactive oxygen species, leading to cellular damage and apoptosis of targeted cells.
Alpha-1 adrenergic receptor antagonist; blocks vasoconstriction and relaxes smooth muscle in blood vessels and prostate.
Treatment of minimally to moderately thick actinic keratoses of the scalp (Grade 1 or 2) in immunocompetent patients,Off-label: other photosensitivity disorders
Hypertension,Benign prostatic hyperplasia
Topical application of a 5% solution to the scalp twice daily.
Topical: Apply a thin film to affected areas once daily. Not for ophthalmic, oral, or intravaginal use.
Not applicable; topical ALA-SCALP is not significantly absorbed systemically. After systemic absorption from photodynamic therapy, terminal half-life is approximately 1 hour due to rapid metabolism.
Terminal elimination half-life is 8-12 hours in adults with normal renal function; prolonged to 18-24 hours in moderate renal impairment (Cr Cl 30-50 m L/min).
ALA is metabolized intracellularly via the heme biosynthesis pathway to protoporphyrin IX (Pp IX).
Hepatic via cytochrome P450 (CYP3A4); active metabolites.
Primarily renal elimination of metabolites; <1% excreted unchanged in urine. Biliary/fecal excretion is negligible.
Renal excretion of unchanged drug accounts for 60-70% of elimination; biliary/fecal excretion accounts for 20-30%; less than 10% metabolized hepatically.
Not characterized; systemic levels are negligible after topical administration.
Approximately 85% bound to albumin; minor binding to alpha-1-acid glycoprotein.
Not applicable for topical route. If systemic exposure occurs, Vd is approximately 0.5 L/kg, consistent with distribution into total body water.
Volume of distribution is 0.6-0.8 L/kg, indicating distribution into total body water.
Topical: Systemic bioavailability is minimal (<1%) due to poor percutaneous absorption and rapid local metabolism.
Oral bioavailability is 70-80% due to first-pass metabolism; IM bioavailability is 90-95%.
No dose adjustment required for renal impairment.
No dose adjustment required for renal impairment.
No dose adjustment required for hepatic impairment.
No dose adjustment required for hepatic impairment.
Safety and efficacy in pediatric patients have not been established.
Safety and efficacy in pediatric patients have not been established.
No specific dose adjustment recommended; use with caution due to potential increased sensitivity.
No specific dose adjustment; use with caution due to potential increased skin fragility.
No FDA black box warning.
None.
Photosensitivity: avoid exposure to sunlight or bright indoor light (e.g., examination lamps, operating room lamps) for at least 40 hours post-application.,Application site reactions: severe stinging, burning, erythema, and edema may occur.,Use sun-protective measures (e.g., wide-brimmed hat, sunscreen) after treatment.,Do not apply to eyes or mucous membranes.
Orthostatic hypotension and syncope, especially with first dose,May cause dizziness, drowsiness, or lightheadedness,Use caution in patients with hepatic impairment,May exacerbate angina or heart failure
Hypersensitivity to aminolevulinic acid or any component of the formulation,Cutaneous photosensitivity at wavelengths of 400-450 nm,Porphyria
Hypersensitivity to alpha-blockers,History of orthostatic hypotension,Micturition syncope,Severe renal impairment,Concomitant use with PDE-5 inhibitors (e.g., sildenafil) due to risk of hypotension
No known food interactions. No dietary restrictions required.
No specific food interactions. However, high-fat meals may increase systemic absorption of topical tretinoin marginally; no dietary restrictions necessary. Avoid excessive vitamin A supplements to reduce risk of hypervitaminosis A.
No evidence of teratogenicity; topical application with minimal systemic absorption. First trimester: unlikely risk. Second/third trimester: no known fetal risks from maternal use.
Pregnancy Category C. First trimester: No adequate human studies; animal studies suggest embryocidal and teratogenic effects at high doses. Second/third trimester: Potential for fetal harm; avoid unless benefit outweighs risk.
Minimal systemic absorption; unlikely to appear in breast milk. M/P ratio not established. Considered compatible with breastfeeding.
Unknown if excreted in human milk; M/P ratio not established. Caution advised due to potential for serious adverse reactions in nursing infants.
No dosage adjustment required; pharmacokinetics unlikely altered due to topical route.
Increased plasma volume may reduce drug levels; consider dose adjustment based on therapeutic drug monitoring. No specific dose adjustment established; use lowest effective dose.
ALA-SCALP is a topical aminolevulinic acid preparation used for photodynamic therapy of actinic keratoses on the scalp. Must be applied by a healthcare professional. Avoid sun exposure to treated area for 48 hours post-application due to photosensitivity. Do not apply to eyes or mucous membranes. Lesions should be prepped by gentle removal of scales and crusts. Use with a compatible light source (blue light). Burning and stinging during light exposure is common; consider pain management strategies.
ALPHADERM (tretinoin 0.05% cream) is a retinoid used for photoaging and acne. Apply a pea-sized amount to dry skin 30 minutes after cleansing; avoid concomitant use of other topical retinoids or exfoliants to prevent irritation. Initiate therapy every other night to build tolerance. Strict sun protection required: use SPF 30+ daily. May cause initial flare of acne (retinoid 'purging') lasting 2-4 weeks. Contraindicated in pregnancy (FDA Category C).
This medication is applied by your doctor to treat precancerous spots on your scalp.,After application, you will need a special light treatment (photodynamic therapy).,Avoid sunlight and bright indoor light on the treated area for 48 hours after the procedure.,You may experience temporary redness, swelling, scaling, or discomfort at the treatment site.,Use sunscreen and protective clothing when going outdoors during the photosensitivity period.,Do not wash the treated area for at least 4 hours after the solution is applied.,Contact your doctor if you experience severe pain, blistering, or signs of infection.
Apply a thin layer to affected areas once daily at bedtime, 30 minutes after washing and drying face.,Avoid excessive sun exposure; use broad-spectrum sunscreen and protective clothing.,Do not use with other medicated topical products, including benzoyl peroxide or salicylic acid.,Expect mild redness, peeling, or stinging initially; this usually subsides with continued use.,Notify your doctor if you are pregnant, planning pregnancy, or breastfeeding.,Store at room temperature away from heat and light.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ALA-SCALP vs ALPHADERM, answered by our medical review team.
ALA-SCALP is a Topical Corticosteroid that works by ALA-SCALP (aminolevulinic acid) is a photosensitizer precursor that is converted intracellularly to protoporphyrin IX (Pp IX), which accumulates in cells with increased heme synthesis, such as rapidly dividing cells. Upon exposure to blue light (BLU-U®), Pp IX produces reactive oxygen species, leading to cellular damage and apoptosis of targeted cells.. ALPHADERM is a Topical Corticosteroid that works by Alpha-1 adrenergic receptor antagonist; blocks vasoconstriction and relaxes smooth muscle in blood vessels and prostate.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ALA-SCALP and ALPHADERM depend on the specific clinical indication. These are both Topical Corticosteroid agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ALA-SCALP is: Topical application of a 5% solution to the scalp twice daily.. The standard adult dose of ALPHADERM is: Topical: Apply a thin film to affected areas once daily. Not for ophthalmic, oral, or intravaginal use.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ALA-SCALP and ALPHADERM in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ALA-SCALP is classified as Category C. No evidence of teratogenicity; topical application with minimal systemic absorption. First trimester: unlikely risk. Second/third trimester: no known fetal risks from maternal use.. ALPHADERM is classified as Category C. Pregnancy Category C. First trimester: No adequate human studies; animal studies suggest embryocidal and teratogenic effects at high doses. Second/third trimester: Potential for fe. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.