At some point in your life, you’ve likely learned about, if not heard of, atoms and their three components: protons, neutrons, and electrons — the 3 building blocks of all atoms in our universe. Protons have a positive charge, electrons a negative charge, and neutrons have a neutral charge. Each element in the periodic table has a specific number of protons, electrons, and neutrons, but what happens when those numbers change?
Water Can Be... Heavier?
Isotopes and Deuterium
Properties of an Element
Each element’s specific number of protons, electrons, and neutrons makes it itself. For example, Hydrogen has 1 proton, 1 electron, 0 neutrons. Uranium has 92 protons, 92 electrons, and 146 neutrons. Changing these numbers has a different effect:
Protons
Changing the number of protons in an atom will make the atom a new element. There’s not much more to it! For example, adding 1 proton to Sodium(11) would make it Magnesium (12).
Neutrons
Changing the number of neutrons in an atom will keep it the same element but will change which isotope it is—we’ll go into more details on what isotopes are below!
Electrons
Changing the number of electrons in an atom will change the electric charge of the atom, making it either positive or negative. These are called ions and can either be a cation (positively charged) or an anion (negatively charged).
What is an Isotope?
As mentioned, an isotope differentiates among the same element with different number of neutrons. Since the number of protons and electrons are the same, the atom will have similar chemical properties, but different physical properties, like mass.
A very common example of an isotope is Uranium (U). U-238 (146 neutrons) accounts for 99% of Uranium on the Earth, however, U-235 (143 neutrons), which is primarily used in Nuclear Fission Reactors, is a significantly small amount compared to U-238.
Isotopes, Deuterium, & Heavy Water
Another important and commonly occurring isotope is deuterium. Deuterium is a Hydrogen atom that has a neutron, when it normally doesn’t. Another name for deuterium is “heavy hydrogen” as it is heavier than normal hydrogen.
Deuterium is naturally abundant in Earth’s oceans and accounts for about 0.0156% of all hydrogen within the ocean.
Deuterium doesn’t just exist on its own and has a whole host of applications, which we’ll explore on the next page!
What is Deuterium Used For?
Now that we know a little bit about isotopes and deuterium, let’s look at how deuterium is used in the pharmaceutical space!
Heavy Water
Since Deuterium behaves similarly to standard hydrogen, it can be used to form water (D2O), which is just like normal water (H2O), but heavier – and is aptly called “heavy water”.
Making Heavy Water
As previously covered, deuterium (and thus heavy water) is naturally abundant, and it can be separated from normal water. This process is extremely energy intensive and consists of cascading enrichment stages. The first step of enrichment only enriches water to 15-20% D2O. From there, distillation is used to bring it to >99% D2O. For a sense of scale, for every 340,000 kg of water fed into the system, you’d get out 1 kg of heavy water!
Deuterium in Pharma
Heavy Water is not just there to be heavy —it’s also becoming more widely used in the pharmaceutical space! Drug stability is a critical aspect to drug development— the drug needs to be stable in its final drug product formulation.
A drug product solution with heavy water has been found to significantly improve the stability of some drug products, as opposed to being in a solution of normal water.
Additionally, not just the drug product, but the API itself could leverage deuterium, replace the hydrogen atoms, and also have improved stability — these are called deuterated drugs.
Why does stability improve with deuterium? Since the deuterium isotope is heavier, the bonds in the molecule are stronger and take more energy to break them, thus causing molecules to stay together longer!
Other Uses for Deuterium
Deuterium and heavy water don’t have uses just in the manufacture of pharmaceuticals — they have a fairly wide range of important uses in other industries!
Nuclear Reactors: heavy water can be used as coolant for a nuclear reactor and as a moderator, to help control the rate of nuclear fission and energy production. Deuterium is also heavily used in nuclear fusion research.
Analytical Chemistry: deuterated solvents are often used for NMR spectroscopy as the deuterium will give off different spectra compared to hydrogen, limiting interference in the data.
Tracing: in chemistry and environmental sciences, deuterium can be used to track chemical and metabolic pathways along with water systems in nature. The deuterium can be measured throughout the process!
