Ceramide NP, AP, and EOP: What the Letters Mean on a Moisturiser

Moisturiser labels often list Ceramide NPCeramide NPModerateCeramide NP · Sphingolipid (non-hydroxy fatty acid, phytosphingosine)The most abundant ceramide class in the stratum corneum; topical replacement improves barrier in controlled trials.Open in the Index → (NP), Ceramide APCeramide APModerateCeramide AP · Skin-identical sphingolipid (α-hydroxy fatty acid)Barrier ceramide (formerly Ceramide 6-II) used with NP/EOP and cholesterol in multi-ceramide moisturisers.Open in the Index → (AP), and Ceramide EOPCeramide EOPModerateCeramide EOP · Skin-identical ω-esterified ceramideLong ω-hydroxy esterified ceramide (formerly Ceramide 1) critical for stratum corneum lamellar organisation.Open in the Index → (EOP) beside "barrier lipid" claims. The letters are structural shorthand, not marketing grades. CIR documented the move from retired numeric INCI names to these letter codes when it assessed ceramides as used in cosmetics [1] [2].

Letter code, not a ranking

A ceramide is an amide of a sphingoid base and a fatty acid. Modern INCI lettering concatenates fatty-acid class then base class. CIR states the mapping shoppers still meet on packaging [1]:

• Ceramide 3 (retired) -> Ceramide NP
• Ceramide 6 II (retired) -> Ceramide AP
• Ceramide 1 / 1A (retired) -> Ceramide EOP

During the interim after the nomenclature change, products could still carry either the retired number or the letter name for the same ingredient [1]. Seeing both styles on older bottles is a labelling transition, not evidence of two different actives.

What N, A, EO, and P stand for

Peer-reviewed stratum corneum lipid work uses the same letter logic CIR later mirrored for INCI [3] [4] [5]:

• N = non-hydroxy fatty acid
• A = alpha-hydroxy fatty acid
• EO = ester-linked omega-hydroxy fatty acid (often very long chain)
• P = phytosphingosine base

So NP is a non-hydroxy fatty acid on phytosphingosine; AP is an alpha-hydroxy fatty acid on phytosphingosine; EOP is an esterified omega-hydroxy fatty acid on phytosphingosine. Motta and colleagues' 1993 scale-lipid paper helped popularise the Cer[NP]/[AP]/[EOS]-style classes later literature still cites [3]. LC/MS profiling papers treat those subclasses as chemically distinct species inside human stratum corneum, not as cosmetic claim tiers [4] [5].

What CIR actually concluded

CIR's Final Report concluded that the reviewed ceramide ingredients (including NP, AP, and EOP under both retired and current names) are safe in cosmetics in the present practices of use and concentration described in that assessment, provided they are not derived from bovine central nervous system tissue [1] [2]. Reported leave-on dermal maxima in the CIR use survey were on the order of 0.2% for several named ceramides in skin-care preparations [1]. Safety clearance is not a clinical ranking of NP versus AP versus EOP for dry-skin outcomes.

How to read a moisturiser panel without inventing ratios

Evidence-first label reading stops at what the panel can support:

1. Confirm named ceramides appear as INCI entries (NP, AP, EOP, or retired numbers), not only as front-of-pack "ceramide complex" language [1].
2. Treat letter codes as structure tags, not potency scores [1] [5].
3. Note companions often discussed with barrier lipids (cholesterol, free fatty acids, phytosphingosine) when they are listed; presence alone does not prove a biomimetic ratio [5].
4. Remember concentration order on an INCI list is approximate; ingredients present below about 1% may be listed with flexibility under US cosmetic labelling practice, so burial near the end is a weak quantitative signal.

FAQ

Is Ceramide 3 the same as Ceramide NP?

Under CIR's nomenclature notes, yes: Ceramide 3 is the retired INCI name replaced by Ceramide NP [1].

Does listing NP, AP, and EOP together prove a formula rebuilds the barrier?

1. It shows the formulator named three subclasses CIR and lipid chemists distinguish structurally. Barrier outcomes depend on the full formula, concentration, vehicle, and the user's skin; CIR assessed cosmetic safety, not comparative efficacy of letter combinations [1] [2].

Should I prefer EOP because older papers call it Ceramide 1?

Retired Ceramide 1 maps to EOP in CIR's account, which marks it as an ester-linked omega-hydroxy phytosphingosine type [1]. That is chemistry, not a shopper ranking. PubMed structural reviews discuss EOP-type species as long-chain linking ceramides in native stratum corneum; they do not establish that any specific leave-on dose outperforms NP or AP in a moisturiser [4] [5].