PABA by Cytoplan Ltd

EFFECTIVE

• Sunburn. Topical PABA prevents sunburn. Details: PABA is an FDA-approved sunscreen (266,8952). PABA seems to be effective during sweating, but not when skin is immersed in water (272). PABA sunscreens can be applied topically in concentrations of 1% to 15% (272).

POSSIBLY EFFECTIVE

• Peyronie disease. Low quality clinical research shows that oral PABA improves Peyronie disease symptoms. Details: PABA is FDA-approved for use in this condition. Clinical research shows that taking the specific PABA product (POTABA, Glenwood LLC.), 3 grams orally four times a day for 8-12 months can reduce penile curvature and deterioration when compared with placebo (1067,8951,67982).

POSSIBLY INEFFECTIVE

• Scleroderma. Clinical research is conflicting, but suggests that oral PABA is not effective for treating scleroderma. Details: Although PABA is FDA-approved for scleroderma, as well as morphea, a localized form of scleroderma, evidence supporting its use is limited. Some retrospective studies suggest it might help for some symptoms of scleroderma, but higher quality evidence shows that it is not beneficial (1071,1073,1074,1075).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. Although there has been interest in using oral PABA for aging skin, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Constipation. Although there has been interest in using oral PABA for constipation, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Headache. Although there has been interest in using oral PABA for headache, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Herpes keratitis. Although there has been interest in using ophthalmic PABA for herpes keratitis, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Infertility. Although there has been interest in using oral PABA for infertility, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Inflammatory myopathies. It is unclear if oral PABA is beneficial in patients with inflammatory myopathies. Details: PABA is FDA-approved for use in dermatomyositis, a type of inflammatory myopathy, but there is limited evidence to support this use (10). PABA is taken as 12 grams orally daily in 4 to 6 divided doses in adults or 220 mg/kg orally daily in 4 to 6 divided doses in children (10).
• Pemphigus. It is unclear if oral PABA is beneficial in patients with pemphigus. Details: PABA is FDA-approved for use in pemphigus, but there is limited evidence to support this use (10). PABA is taken as 12 grams orally daily in 4 to 6 divided doses in adults or 220 mg/kg orally daily in 4 to 6 divided doses in children (10).
• Systemic lupus erythematosus (SLE). Although there has been interest in using oral PABA for SLE, there is insufficient reliable information about the clinical effects of PABA for this purpose.
• Vitiligo. Although there has been interest in using oral PABA for vitiligo, there is insufficient reliable information about the clinical effects of PABA for this purpose. More evidence is needed to rate PABA for these uses.

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LIKELY SAFE ...when used topically and appropriately. PABA is FDA approved for topical use and there have not been reports of significant toxicity (266,272).

POSSIBLY SAFE ...when used orally and appropriately (10). PABA is an FDA-approved drug, but some potentially serious side effects have been reported (10).

POSSIBLY UNSAFE ...when used orally in high doses. Doses greater than 12 grams per day have been associated with leukopenia (1061).

CHILDREN: LIKELY SAFE
when used topically and appropriately (266,272).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately (10). PABA is an FDA-approved drug for use in children, but serious side effects have been reported (10).

CHILDREN: POSSIBLY UNSAFE
when used orally in high doses. Doses greater than 220 mg/kg/day have been associated with fatal toxic effects (1061).

PREGNANCY AND LACTATION: LIKELY SAFE
when used topically and appropriately (266,272). There is insufficient reliable information available about the safety of the oral use of PABA during pregnancy and breast-feeding; avoid using.

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CORTISONE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of PABA and cortisone may increase the effects of cortisone.  Details Preliminary clinical research shows that PABA decreases the metabolism of cortisone (4488). Dose adjustments of cortisone may be necessary.

DAPSONE (Avlosulfon) Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = D Theoretically, concomitant use of PABA and dapsone may decrease the effects of dapsone.  Details Preliminary clinical research shows that PABA inhibits the antibacterial effects of dapsone (4488). Avoid concurrent use (266).

SULFONAMIDE ANTIBIOTICS Interaction Rating = Major Do not take this combination. Severity = Moderate •  Occurrence = Likely •  Level of Evidence = D Theoretically, concomitant use of PABA and sulfonamide antibiotics inhibits the antibacterial effects of sulfonamide.  Details Sulfonamide antibiotics competitively inhibit folic acid synthesis from PABA. Excess PABA may overcome the folate depleting effect of the sulfonamides (10). Avoid concurrent use.

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General ...Orally and topically, PABA is generally well tolerated.
Most Common Adverse Effects:
Orally: Anorexia, dyspepsia, fever, nausea, rash, vomiting.
Topically: Dermatitis, paradoxical photosensitivity.
Serious Adverse Effects (Rare):
Orally: Hepatotoxicity.

Dermatologic ...Topically, PABA can cause contact dermatitis and sometimes paradoxical photosensitivity (272).

Gastrointestinal ...Orally, the most commonly reported side effects of PABA are diarrhea, nausea, vomiting, anorexia, dyspepsia, fever, and rash (1074). PABA should be discontinued if adverse effects prevent the patient from eating (10). In one report, up to 25% of patients discontinued PABA due to intolerance of side effects (1074).

Hematologic ...High dose PABA (up to 48 grams per day) can cause decreased white blood count below 4000 mm3 in approximately 30% of patients (1061).

Hepatic ...Liver toxicity, including fatal hepatitis has been reported in patients taking PABA in high doses (12-48 grams per day) (1061,1094). In one case, 12 grams per day for 2 months caused liver toxicity (1094). Increased liver function tests from PABA have also been noted (1084), and jaundice was reported in one case of treatment with PABA (68049). Despite these reports, a study reviewing the charts of 274 patients with scleroderma who were taking the potassium salt form of PABA as treatment found no evidence of hepatotoxicity (1065).

Immunologic ...Orally, PABA can cause allergic reactions including fever and skin rash (1074).

Neurologic/CNS ...Orally, PABA may cause headaches, which resolve upon discontinuation of treatment (1074).

Other ...Death has been reported in 3 children treated with 24 grams of PABA per day for rheumatic fever or arthritis. At autopsy, all had fatty changes in the liver, kidney, and myocardium (1061). Topical PABA and its derivatives have a tendency to discolor clothing due to a photo-oxidative reaction (68025).

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