Durapex 100, made by SixPex, is the brand name for Nandrolone Phenylpropionate—most people just call it NPP. It’s an anabolic steroid, pretty fast-acting, and closely related to Deca-Durabolin (Nandrolone Decanoate). The main difference? NPP doesn’t stick around in your system as long. It kicks in quick, but it also clears out fast.

What’s inside? 
You’re getting 100 mg of NPP per milliliter, in an oil-based injectable. SixPex manufactures it.

Why use it? 
NPP helps your body grow and repair tissue, plain and simple.

If you’re after muscle, NPP ramps up protein synthesis and helps your body hold onto nitrogen. That means you can put on lean muscle faster. It’s also famous for helping your joints—by boosting collagen and bone mineral content, it can cut down on joint pain and make heavy lifting a little easier on your body. Recovery is another big one: NPP helps your muscles bounce back quicker after those brutal workouts. Plus, it pushes up your red blood cell count, which means your muscles get more oxygen. More oxygen equals better endurance.

How do you use it? 
First off, NPP counts as a controlled substance, so a doctor needs to supervise its use.

Medically, people used to get just 25 to 50 mg a week. In bodybuilding or performance circles, guys usually go with 200 to 400 mg a week, split into shots every other day. Women sometimes use 25 to 50 mg a week, but honestly, even that’s risky—there’s a real chance of developing masculine traits. Most people run it for 8 to 12 weeks at a time. You inject it deep into the muscle—glutes, thighs, or delts are the usual spots.

What about side effects?
 Well, there’s a list. You can get acne, lose hair if you’re prone to male pattern baldness, or notice more body hair. NPP isn’t great for your cholesterol and might bump up your blood pressure. The big one: it shuts down your natural testosterone, hard. That means when you’re done, you’ll need Post Cycle Therapy to get your hormones back on track.