What Makes ContraPest<sup>®</sup> So Effective?

Feb 10

Learn More About Its Innovative Active Ingredients and Why Rats Can’t Resist It

ContraPest is the first EPA-registered contraceptive bait. It’s designed to lower birth rates of male and female Norway rats (Rattus norvegicus) and roof rats (R. rattus). When used in conjunction with other integrated pest management (IPM) strategies, ContraPest not only helps reduce rat populations but also prevents them from bouncing back. It’s a great option for getting rid of rats, since traditional strategies such as poisons can leave rats alive long enough to breed and multiply.

As a contraceptive bait, ContraPest is undoubtedly effective. In field studies, when two major American cities chose to integrate ContraPest into their rat control practices, they achieved significant results. When Washington, D.C. added ContraPest to their IPM, they saw a 90% reduction in rat activity at two sites over the course of a year. And when San Francisco Recreation and Park personnel implemented ContraPest into an ongoing IPM program, they recorded a 65% drop in burrow counts over a year.

The results are impressive. And they beg the question: what makes ContraPest so effective?

In this month’s post, we’re going to answer that by taking a closer look at the ContraPest formula. We’ll discuss its two active ingredients, as well as their modes of action, to help explain why ContraPest works so well. And we’ll discuss the sweet, fatty “milkshake” consistency that makes it irresistible to even the most discriminating rat palate.

It’s What’s Inside That Counts

“Better Ingredients, Better Pizza,” goes the Papa John’s slogan. And while pizza has literally nothing to do with ContraPest–except for Pizza Rat, of course!–we can’t deny the sentiment still applies. The bottom line is that ContraPest works well because its two active ingredients do precisely what you need them to do, and in just the right way.

ContraPest’s active ingredients are 4-vinylcyclohexene diepoxide (VCD) and triptolide. They work in tandem to reduce fertility in both male and female rats. VCD is a standard industrial chemical that depletes primary and primordial follicles in the ovary. Triptolide, derived from the thunder god vine (Tripterygium wilfordii), has been used in ancient Chinese medicine and certain over-the-counter supplements. Triptolide has long been known to affect spermatogenesis and the growing follicles in females.

It’s important to note these ingredients suppress fertility in rats, but they don’t make them sterile. They’re only able to work through repeated consumption, and the effects of ContraPest are reversible over time if the bait is removed. This, in conjunction with the relatively low dose that rats need, minimizes any risk to predators or non-target species.

So Your Rats Took the Bait. Now What?

When rats eat ContraPest, the bait quickly gets to work. After ingestion, both active ingredients are absorbed in about 15 minutes.

To understand how ContraPest reduces fertility, let’s take a look at its mode of action. Triptolide affects the reproductive systems of female and male mammals, but we know that males are far more sensitive to its effects. It has the strongest effect on epididymal sperm and works to reduce the number and motility of these gametes. In female rats, triptolide results in few to no ovulations and the depletion of the secondary follicles in the ovary.

When VCD is ingested, it depletes the primordial and primary ovarian follicles in mammals. Although VCD interferes with ovarian function, it’s important to note that it does not affect endocrine function and therefore is not an endocrine disruptor.

It’s the innovative combination of VCD and triptolide into a single formulation that makes ContraPest unique and enables it to reduce fertility in both sexes. This provides a double layer of defense against rat reproduction.

“Okay, Now That Was Tasty”

If rats could leave Yelp reviews, that’s what they’d say about ContraPest.

Because ContraPest only works if rats keep eating it, we had to make it true “ratnip”–something rats go crazy for and return to time and again.

To appeal to the rat palate, we developed ContraPest as a fatty, sweet-tasting liquid. The flavor profile is delicious to rats and the liquid formulation helps them reach their daily liquid intake requirements, which are pretty steep—about 10% of their body weight.

Rats will actually choose to consume ContraPest while in the presence of other food and water sources. That’s a pretty sincere endorsement if you ask us.

ContraPest Keeps Rats From Coming Back

We put years of research into ContraPest to help you get rid of rats. If you’re already using it, or you’re curious about how it can help you make troublesome rats go away, we’re standing by to help. Feel free to drop us a line or visit our store page for more details.

Contrapest Kit