Table 6.

Regulatory information about some hydrogel ingredients [158].

Common Name	USP-NF Name	Preferred Substance Name (USFDA)	EP Name	CAS No.	Maximum Potency per Unit Topical Dose(as per USFDA)	Relevant Physico-Chemical Properties	GRAS Listed
Alginate	Alginic acid, sodium alginate	Sodium alginate	Alginate, sodium	9005-38-3	0.25% w/w	Dissolves in water and forms a viscous solution	✓
Collagen	Gelatin	Type II Collagen	Collagen	9007-34-5	8% w/w		✓
Gelatin	Gelatin	Gelatin	Gelatin	9000-70-8	350 mg		✓
PEG 200	Polyethylene glycol 200	Polyethylene glycol 200	Polyethylene glycol 200	112,607	39% w/w	Viscosity 3.9–4.8 mPas at 98 °C	✓
PEG 1000	Polyethylene glycol 1000	Polyethylene glycol 1000	Polyethylene glycol 1000	25,322,683	0.5% w/w	Viscosity 16–19 mPas at 98 °C
PEG 1600	Polyethylene glycol 1600	Polyethylene glycol 1600	Polyethylene glycol 1600	25,322,683	29.7% w/w	Viscosity 28–36 mPas at 98 °C	✓
PEG 300	Polyethylene glycol 300	Polyethylene glycol 300	Polyethylene glycol 300	25,322,683	57% w/w	Viscosity 5.4–6.4 mPas at 98 °C	✓
PEG 400	Polyethylene glycol 400	Polyethylene glycol 400	Polyethylene glycol 400	25,322,683	99% w/v	Viscosity 6.8–8 mPas at 98 °C	✓
Polyacrylic acid	Poly(acrylic acid)	Polyacrylic acid	Polyacrylate	9003-01-4	196 mg	Viscosity 50–200 mPas at 20 °C	✓
Polyvinyl alcohol	Polyvinyl alcohol	Polyvinyl alcohol	Polyvinyl alcohol	9002-89-5	140 mg		✓
Polyacrylamide	Polyacrylamide	Polyacrylamide	Polyacrylamide	9003-05-8	5% w/w		✓

USP NF—United States Pharmacopeia (USP) and the National Formulary (NF); USFDA—United States Food and Drug Administration; GRAS—Generally recognized as safe.