RCP for Hair Growth: How Redensyl, Capixyl and Procapil Work Together

RCP is shorthand for three branded active blends: Redensyl, Capixyl and Procapil. Each was designed by a different ingredient maker for a different weak point of a thinning follicle, and together they divide the work of keeping that follicle growing. One lever was never the whole story, so the formula gives each blend a defined job.

The follicle in one minute

The hair you can see is finished keratin. Everything an ingredient can influence happens below the skin, in the follicle.

At the base sits the dermal papilla, a small cluster of signaling cells with its own blood supply. Think of it as the control room: it sends the growth factors that tell the follicle how big a hair to make and for how long. Above it, the bulb is the factory where dividing cells become the hair shaft. Along the side, the outer root sheath holds a reserve workforce of stem cells, concentrated in a region called the bulge. Around all of it is the extracellular matrix, a network of proteins such as collagens and laminins that holds the follicle in place. That is the foundation.

Follicles cycle. A growing phase (anagen) can last years on the scalp, followed by a short transition and a resting phase (telogen) before the old hair sheds and a new one starts. In pattern hair loss, the hormone DHT, made from testosterone by the enzyme 5-alpha-reductase, gradually shortens growing phases and shrinks susceptible follicles. Researchers therefore measure the share of hairs that are growing versus resting, and they measure over months, because a cycle moves slowly in both directions.

With that map, the three blends make sense.

Decode the blends on the label

You will not find "RCP" or even "Capixyl" in an ingredient list. Each trade blend appears as its separate parts. This table connects the names.

Swipe to see all four columns →

You can check every one of these names in the current Loxstar ingredient list.

Redensyl: start new growth

Redensyl's design starts from an observation about thinning scalps: the reserve stem cells in the outer root sheath become less productive, and the dermal papilla communicates with them less. The result is a follicle that is slow to start its next growing phase.

Its main active, dihydroquercetin glucoside (DHQG), is a plant polyphenol from larch. In the maker's cell studies, DHQG increased division of outer-root-sheath stem cells while helping them keep their stem-cell identity, raised a survival signal (BCL2) and a growth-phase signal (beta-catenin), and increased the metabolic activity of dermal papilla cells. The green tea component, an EGCG glucoside, reduced IL-8, a messenger of local inflammation, in stressed skin cells by about a fifth. Glycine is a building block of hair's keratin proteins, and zinc is a cofactor that helps build them.

What was tested: in the maker's clinical study, 26 men with moderate pattern hair loss applied 3% Redensyl or a placebo to the whole scalp once a day for three months. Progress was measured by phototrichogram: magnified photos of a small clipped patch of scalp, used to count growing versus resting hairs. The Redensyl group's share of growing hairs rose 9%, resting hairs fell 17%, and density rose 8%. The maker reports that 85% of volunteers improved.

In plain terms: Redensyl is aimed at the control room and the reserve workforce, the cells that decide whether a new hair gets started.

Capixyl: hold the follicle, turn down the DHT signal

Capixyl comes at the follicle from the outside in. In their 2013 paper in the Journal of Cosmetic Science, Loing and colleagues at Lucas Meyer framed hair loss around three drivers: androgen activity, loss of the matrix proteins that anchor the follicle, and low-grade inflammation. Capixyl's two halves split those jobs.

Acetyl tetrapeptide-3 is a four-amino-acid peptide built to mimic a signal fragment the body releases when tissue remodels. In lab tests on human fibroblasts, the connective-tissue cells that make these proteins, collagen III rose 65% and laminins nearly fourfold after three days. In human skin samples thinned by a steroid, the peptide restored collagen VII, one of the proteins that literally fastens tissue layers together, within two days.

Red clover is standardized to biochanin A, a plant compound that inhibited both forms of 5-alpha-reductase in cell assays (64% for type 1 and 93% for type 2 at the tested concentration). Combined with the peptide, it also cut IL-8 release from stressed skin fibroblasts by a third to a half.

What was tested: 30 volunteers with mild to moderate hair loss applied 20 drops of a lotion containing 5% of the red clover and peptide mixture, or a placebo, each night for four months. Measured with TrichoScan, a similar photo count, the active group's share of growing hairs rose 13% and resting hairs fell 29%, while the placebo group moved the other way.

For how a peptide serum compares with minoxidil, and how to choose between them, see Peptide Hair Serum vs. Minoxidil.

In plain terms: Capixyl repairs the foundation the follicle sits in and turns down the enzyme behind the DHT signal.

Procapil: hold the follicle, keep it supplied

Procapil is three molecules with three supporting roles.

Biotinoyl tripeptide-1 is GHK, a natural three-amino-acid peptide involved in tissue repair, with biotin attached. Sederma calls it a "vitaminated matrikine": a repair signal with a vitamin partner built in. It is not a biotin supplement and it is not the copper peptide GHK-Cu; it is its own molecule. In the maker's follicle culture work, it increased proliferation of root-sheath cells and strengthened staining of laminin 5 and collagen IV where the follicle meets the surrounding tissue. Those are anchoring proteins again, this time at the follicle's own border.

Apigenin, a citrus flavonoid, is included to support local microcirculation, the follicle's supply line. Oleanolic acid, from olive leaves, inhibits 5-alpha-reductase.

What was tested: in Sederma's clinical study, 35 men applied a 3% Procapil lotion or a placebo twice daily for four months, measured by videotrichogram, another magnified count of growing and resting hairs. The ratio of growing to resting hairs rose from 2.84 to 3.13 with Procapil and slipped from 2.61 to 2.54 with placebo.

In plain terms: Procapil holds the follicle at its border, keeps its supply line open and adds a second check on DHT production at the scalp.

How the three jobs fit together

Follow one follicle through a cycle and the division of labor becomes clear.

DHT is what shortens growing phases, so two of the formula's ingredients, biochanin A and oleanolic acid, act on the enzyme that makes it, right at the scalp. A follicle in its resting phase still has to restart, and that is Redensyl's job: activating the reserve cells and the papilla that signal a new growing phase. Once a new hair is growing, it needs a secure anchor through a long anagen, which is where the two peptides come in: acetyl tetrapeptide-3 rebuilds the matrix from outside the follicle, and biotin-GHK reinforces its border. Around all of it, apigenin supports the blood supply, and the green tea and red clover components calm the low-grade inflammation that Loing's team identified as the third driver.

No single blend covers all three jobs. The overlap on anchoring and on the DHT enzyme is deliberate: those are two of the three drivers Loing's team identified, so the formula addresses each one from two directions.

What happened when all three were tested together

The combination itself has been studied once in a published trial. Karaca and Akpolat, writing in the Journal of Cosmetology and Trichology in 2019, randomized 120 men aged 18 to 55 with Norwood-Hamilton stage II to V hair loss (from early temple recession to clear crown thinning) to an RCP solution or 5% minoxidil, each applied as 1 mL twice daily for 24 weeks. 106 men completed the study.

On the investigators' density assessment, 64.7% of the RCP group showed moderate or significant recovery versus 25.5% of the minoxidil group, which the authors report as 2.54 times as many. On a seven-point global photographic scale, 88.9% of the RCP group improved versus 60% of the minoxidil group. More men in the RCP group agreed that their thinning area had shrunk. The authors reported slight irritation in the minoxidil group and no serious adverse effects, and they called for larger studies of the blends used alone and alongside minoxidil.

This is the study cited on the Loxstar product page, which states that the serum uses the RCP complex at the same concentrations as this study.

What to expect, and when

Every human study above measured over three months or more: three months for Redensyl, four for Capixyl and Procapil, 24 weeks for the combination. That timing follows from the hair cycle. A resting follicle has to enter a new growing phase, and the new hair has to grow long enough to see.

The usage note on Loxstar's product page says most users see "reduced shedding by week 4, thicker hair by week 8, and new growth by week 12," and the product FAQ recommends at least 90 days of daily use. Take a starting photo with the same light, part and angle you will use later, then compare on a calendar, not after each application.

RCP inside Loxstar

RCP is the core of the current Loxstar Peptide Hair Growth Serum, not the whole formula. Around it sit AnaGain, a pea sprout extract researched for the signals that start a new growth phase, liposomal caffeine, and supporting botanicals including rosemary, ginseng, ginkgo and ashwagandha. RCP covers the three core jobs, starting growth, holding the follicle and turning down the DHT signal, in one daily step.

The routine is built to be run, not just admired: once a day on a clean scalp, a pea-size amount from the dropper on thinning areas, 30 seconds of massage and five minutes before styling. If your hair is long or dense, our scalp application guide shows how to get the serum onto skin rather than strands.