Some Basic Facts about Active Pharmaceutical Ingredient Excipients for Drug Discovery

Pharmaceutical excipients are substances formulated together with active pharmaceutical ingredients (APIs) of the drug, and excipients account for most of the drug composition. Excipients are designed to interact with and enhance the properties of APIs.

Excipients have various functions. In addition to acting as carriers, and improving stability, pharmaceutical excipients are also conducive in terms of solubilization, sustained release, and controlled release. Overall, they are important components that may affect the quality, safety and effectiveness of drugs.

Excipients can be classified by source, function, route of administration, and the like.

By Source

They can be divided into natural, semi-natural and fully synthetic excipients.

By Function

They can be divided into solvents, propellants, solubilizers, cosolvents, emulsifiers, colorants, binders, disintegrants, fillers, lubricants, wetting agents, osmotic pressure regulators, stabilizers, glidants, correctives flavoring agents, preservatives, suspending agents, coating materials, fragrances, anti-adhesives, integrating agents, penetration enhancers, pH modifiers, buffers, plasticizers, surfactants, foaming agents, defoaming agents, thickeners, inclusion agents, humectants, absorbents, diluents, flocculants and deflocculants, filter aids, release blockers, etc.

By Route of Administration

Excipients can be added to develop different dosage forms, such as oral, injection, mucosal, transdermal or topical administration, nasal or oral inhalation administration, and ocular administration.

Potential Adverse Reactions Caused by Excipients

The adverse reactions caused by the excipients added to the drug are related to the properties of the excipients themselves. Some excipients themselves have certain toxicity, once the concentration is too high, or used in a long term, they may cause adverse reactions. For example, when propylene glycol is used as an excipient to dissolve poorly soluble drugs, and if administered in large doses, propylene glycol will be converted into lactic acid by acetaldehyde dehydrogenase, and adverse reactions such as lactic acidosis and hemolysis may occur. The long-term high-dose infusion may also cause some damage to the kidneys.

In addition, during the preparation process, ethanol is used as a solvent for many insoluble drugs. However, ethanol may induce burning and pain during the medication process, and if the application site is close to nerve tissue, it may also cause nerve damage. For example, when cephalosporin antibiotics are used, if they are combined with drugs containing ethanol as excipients, there may be disulfiram-like reactions, with symptoms such as body flushing, headache, nausea, vomiting, decreased blood pressure, and even shock.

Preservatives are also excipients that need to be added in many liquid preparations (such as eye drops and nose drops) to prevent the growth of microorganisms and ensure the stability of the preparation. However, the long-term use of these eye drops containing preservatives will cause pathological damage to the ocular surface. The long-term use of nasal drops containing preservatives will cause damage to the ciliated tissue in the nasal cavity, thereby reducing the respiratory system's resistance to bacteria and its ability to scavenging dust particles.

Adverse reactions caused by excipients are also related to the patient constitution. In fact, for most patients, a little excipient has no effect, but due to individual differences, a very small amount of excipients may cause allergic or other adverse reactions in a very small number of patients. For example, lactose is a diluent for many tablets and capsules, but for patients with lactose intolerance, it may cause adverse reactions such as diarrhea and abdominal pain. Tartrazine is a colorant excipient, but there is cross-allergy to aspirin, and individual patients may experience acute bronchospasm, urticaria, and even severe angioedema or anaphylactic shock.

CD Formulation’ cGMP-compliant laboratory is equipped with a team of experts specialized in drug formulation and manufacturing. Their expertise can facilitate drug development especially in regard to the choice and preparation of various excipients. Customized pharmaceutical excipients will be manufactured to meet clients’ requirements for different projects. Meanwhile, this company, with an innovative spirit and a down-to-earth attitude, is also missioned to help researchers solve the difficulties encountered in the different stages of drug research and development.