Best Injection Site for Ozempic
What is Ozempic?
Ozempic, also known as semaglutide, is a prescription medication that recently gained attention due to its role as a weight loss drug. Originally developed by Novo Nordisk, Ozempic is a glucagon-like peptide-1 receptor agonist, which means that it mimics action of a hormone (chemical messenger molecule) called GLP-1, which is released from the stomach when we eat.
Ozempic is used to regulate blood sugar levels and reduce the risk of heart-related complications in patients with type 2 diabetes, and in patients with heart disease [1, 2]. This is achieved by lowering blood glucose, and aiding in weight loss [3].
How and where to inject Ozempic?
Ozempic is administered as a subcutaneous injection, which means that it is injected under the skin. The drug comes in a pre-filled disposable injection pen, with the dose ranging from 0.25 milligrams to 2 milligrams. Dosing depends on the individual patient.
Patients administer Ozempic at home using the injection pens. The manufacturer indicates that the drug should be injected in the abdomen (stomach), upper arm, or thigh [1, 2]. It is recommended to rotate the injection sites to eliminate pain, bruising and reduce risk of infection.
Abdomen vs. Thigh: Where to inject?
Different parts of the body have different anatomies, and that includes the skin and the layers underneath it. When a drug is injected subcutaneously, it reaches the layer of tissue under the skin, where it diffuses through the interstitial fluid (fluid that fills the spaces between cells), and eventually reaches the bloodstream.
Studies have demonstrated that absorption of some drugs can vary depending on the injection site. Absorption is important parameter when designing a drug, as the aim is to have the most efficient delivery of drug to its target as possible.
For example, research on insulin concluded that the absorption rate can be higher when injected to the abdomen compared to the thigh. A study found that insulin was absorbed 86% quicker in the abdomen [4]. Another study found that insulin injected in the abdomen was more effective at lowering blood glucose more quickly than when injected in the thigh [5].
However, different drugs have different site preferences. For instance, NPH (isophane) insulin, which is a type of insulin formulation that acts more slowly and lasts for longer (thus eliminating the need for frequent injections) absorbs better in the thigh than in the abdomen [6].
Understanding Subcutaneous Drug Absorption
Subcutaneous injections are commonly used for drug delivery, particularly for molecules that do not absorb well when taken orally as a tablet, or for drugs with a controlled release profile [7]. However, a variety of anatomical, physiological and chemical factors influence how a drug behaves following a subcutaneous injection:
- Drug properties - The chemical properties of the molecule itself matter the most. Size is an obvious factor - large molecules tend to absorb more slowly. Membrane permeability, meaning how well a drug crosses the cell membrane, is another important factor [8, 9].
- Formulation - meaning what else is in the injection with the drug molecule. Some drugs are formulated with viscous, oily substances to slow down their release.
- The injection process - the injection rate (how quickly is the injection pushed in), and volume of fluid injected affects tissue backpressure during the injection (tissue 'bouncing back'), which in turn influences how the drug absorbs [10].
- Tissue properties and physiology - Tissue can behave differently based on internal and external factors. Body temperature, exercise, body position, food or stress can impact the pharmacokinetics of subcutaneously administered drugs by modifying the permeability and porosity of the tissue via cascades of signalling pathways [10, 11].
- Electrostatic interactions - these are attractive or repulsive forces between charged particles. To cross membranes or fulfil cellular functions, molecules often have a positive or negative charge. Positively charged drugs tend to bind to subcutaneous tissue, and therefore may absorb more slowly. Furthermore, the strength of this bond depends on pH in the tissue [12].
These factors, and others, can be manipulated in the process of drug design, resulting in engineering a formulation with the optimal absorption rate for the given molecule and its target.
Conclusion: Is it better to inject Ozempic in the stomach or the thigh?
As for Ozempic, there is no evidence or data suggesting that the absorption of the drug would differ between the recommended injection sites. It is important to follow the instructions given by manufacturer of the drug, as well as your doctor to ensure that administration of Ozempic is safe and effective.