Topical gel vs oral tablets: the route divide
Every row cites its source. Where a cell reflects our own reading of the evidence rather than an external source, the row says so.
The same molecule at two exposures two orders of magnitude apart. Every row cites its source; this is the table the rest of the site keeps pointing back to.
| Aspect | Topical gel (5% / 7.5%) | Oral tablets (25 / 100 mg) | Source |
|---|---|---|---|
| Approved use | Acne vulgaris (7.5%: ages 9 and up) | Dermatitis herpetiformis; all non-resistant leprosy | source |
| Systemic exposure | AUC 282 to 415 ng.h/mL; about 1% of a 100 mg oral dose | 52,641 ng.h/mL from a single 100 mg dose; chronic troughs around 2,300 ng/mL | source |
| Hemolysis | Transient lab changes in the G6PD crossover trial; no clinical anemia; largest hemoglobin drop was in the vehicle group | Dose-related and near-universal: 1 to 2 g hemoglobin loss in almost all patients | source |
| Methemoglobinemia | Postmarketing case reports, including pediatric exposures; labels teach cyanosis recognition | The most common drug cause in hospital series: 42% of 138 cases, mean peak 7.6% | source |
| Agranulocytosis and hypersensitivity | Not observed in topical trials (oral experience carried on the label as class information) | Deaths reported; about 1 per 3,000 patient-years agranulocytosis; DHS in 1.4% with 9.9% fatality | source |
| Required monitoring | None in the current labels | CBC weekly for month 1, monthly for 6 months, then semi-annually; liver function when feasible | source |
| G6PD deficiency | No testing required (2005 label required it; deleted in 2008 after the crossover trial) | Caution: exaggerated dose-related hemolysis; treat anemia first, monitor hemoglobin | source |
| Contraindications | None listed | Hypersensitivity to dapsone or derivatives | source |
| Pregnancy and lactation | No human data; low absorption is the label's stated basis | Category C; excreted in breast milk in substantial amounts; neonatal hemolytic reactions possible | source |