Fluorinated Compounds and Pharmaceuticals-what's the Connection?

During the last several years, a great deal of pharmaceutical research has focused on the use of fluorinated compounds In fact, by around 1990, approximately 220 fluorinated pharmaceuticals were in use, comprising nearly 8% of the synthetic drug market. Since that time the use of fluorinated pharmaceuticals has increased rapidly. These fluorinated compounds play an increasingly important role in the modern pharmaceutical industry, and currently an estimated 30% to 50% of all pharmaceutical products contain fluorinated chemicals.

Current Pharmaceutical Uses of Fluorinated Compounds

Fluorinated compounds are present in a wide variety of pharmaceutical products, including the following types of products:

• General anesthetics
  
• Antacids
  
• Anti-fungal drugs and antibiotics
  
• Antidepressants, anti-psychotics, and anti-anxiety medications
  
• Steroids and anti-inflammatory agents
  
• Anti-malarial drugs
  
• Cholesterol-lowering agents
  
• Chemotherapeutic agents for cancer treatment

A Closer Look at Some Common Pharmaceutical Applications

Two of the most commonly-prescribed antidepressants contain fluorinated compounds. These are Prozac and Paxil, the third and fifth most commonly-prescribed anti-depressants in America, respectively. Both of these are known as "selective serotonin reuptake inhibitors", which means they work by preventing presynaptic transmission of serotonin to somal neurons. This means, Prozac and Paxil make increased levels of serotonin available for stimulating neurons in the brain, thus reducing symptoms of depression.

Another common application of fluorinated compounds is in the chemotherapeutic treatment of certain types of cancers. A chemotherapeutic agent called Fluorouracil, which belongs to a family of drugs known as anti-metabolites, has been used in the treatment of cancer for approximately 40 years.

Fluorouracil is an analog of a molecule called uracil, which is used by all cells for DNA replication. The fluorinated analog interrupts the proliferation of cancer cells by masquerading as the naturally-occurring uracil, and preventing cells from synthesizing new DNA molecules which are needed for replication. While Fluorouracil does also act in healthy non-cancerous cells, it is taken up and used quicker in cancerous cells. Fluorouracil is used mainly for the treatment of pancreatic and colorectal cancers, where it has been in use for several decades, in combination with another chemotherapeutic agent called Leucovorin.

Anti-bacterial and anti-fungal agents known as Ciprofloxacin and Fluconazole, respectively, are also fluorinated compounds. Ciprofloxacin works by preventing bacterial cells from correctly synthesizing new DNA molecules, and in turn preventing cells from dividing. Unlike many other antibacterial agents, Ciprofloxacin is active against both Gram Positive and Gram Negative bacteria, greatly increasing its range of applications. Fluconazole inhibits the function of a fungal enzyme called cytochrome P450, which prevents growth of fungal cells due to instability of cell membranes.

The Growing Popularity of Fluorinated Pharmaceuticals

Interestingly, organic fluorinated compounds are rarely found in nature, and the few that do exist are highly toxic. Why, then, are fluorinated compounds so commonly used in the pharmaceutical industry? There are several reasons for the now widespread use of fluorinated pharmaceuticals.

The first important factor is that organic fluorinated compounds are inherently bioactive.
Second, introducing fluorine into a bioactive compound that does not already contain it improves the pharmacological properties of that compound in many cases. Simply by adding fluorine, many drugs can be made more potent, meaning that a lower dose may be used to achieve the same effect.

Third, the addition of fluorine to bioactive compounds does not usually change their shape to any great degree. This is a crucial factor in the pharmaceutical industry, because changing the shape of a bioactive compound may decrease its potency, or completely inhibit its bioactivity.

The fourth important feature of fluorinated pharmaceuticals is that the addition of fluorine increases the stability of these products, due to the strong covalent bond formed between fluorine and carbon. However, it should be noted that this is sometimes a drawback, as this increased stability can reduce the metabolic degradation rate of some fluorinated pharmaceuticals.

Finally, the increasing ease of use of fluorinated compounds is also noteworthy. In its elemental form, fluorine is a highly reactive and toxic gas, which has limited its use to specially-equipped laboratories in the past. However, in recent years specialized equipment for generating and handling fluorine has become more widely available.

As the use of fluorine has become more mainstream, its range of potential applications has increased dramatically. For example in many cases, fluorine may be able to be substituted in currently known chlorinated or brominated pharmaceuticals with relative ease, potentially increasing their potency.