Doxylamine

Separation type: Bridge Ion Separation Technology, or BIST™

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High Performance Liquid Chromatography (HPLC) Method for Analysis of Acetaminophen, Dextromethorphan, Pseudoephedrine, Doxylamine

Nyquil is a combination of medicines used to treat headaches, fever, body aches, cough, runny nose, sneezing, and sore throat caused by allergies, the common cold, or the flu. Nyquil contains the active ingredients acetaminophen, dextromethorphan HBr, doxylamine succinate, and sometimes, phenylephrine HCl. Acetaminophen is a pain reliever and fever reducer. Dextromethorphan is a cough suppressant. It affects the cough reflex in the brain that triggers coughing. Doxylamine is an antihistamine that reduces the effects of the natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. Pseudoephedrine is used to relieve nasal congestion caused by colds, allergies, and hay fever. It is also used to temporarily relieve sinus congestion and pressure. All active compounds of Nyquil can be separated in HPLC on a BIST B+ column. The analytical method uses acetonitrile (ACN) gradient and water with sulfuric acid (H2SO4) as buffer and UV detected at 210 nm.

Pyridoxine, also known as Vitamin B6, is an essential nutrient required by the body to produce red blood cells and for proper nerve functioning. Doxylamine is a common treatment for insomnia. When taken together, they can treat morning sickness in pregnant women.

Pyridoxine and Doxylamine can be retained, separated, and detected on a normal-phase Primsep S using an isocratic analytical method with a simple mobile phase of water, Acetonitrile, and an Ammonium Formate buffer. This analysis method can be detected in the low UV regime at 270 nm.

NyQuil is a cough medication produced by Procter&Gamble. It consists of acetaminophen, pseudoephedrine, doxylamine and dextromethorphan. Most of the analytical HPLC methods include either use of ion-pairing reagent or a gradient elution. Mixed-mode chromatography allows to replace long gradient method with short isocratic method. All four compounds are well separated within 3-5 minutes. Methods can be optimized for analysis of other cough composition containing general cough suppressants and pain killers. Method is robust and being validated at several drug companies.

Mixed-mode chromatography allows to separate various hydrophobic and hydrophilic drugs in one HPLC method. Presence of at least two mechanism of retention allows adjust selectivity of separation by changing three parameters: amount of acetonitrile, buffer concentration and buffer pH. Seven common drugs are separated on a Primesep C trimodal HPLC column in gradient method. Method provides alternative selectivity to traditional reversed-phase chromatography. Operational range in which basic compounds are retained the most is from pH 3 to 5. At higher pH, longer retention can be achieved. Mixed-mode chromatography provides longer retention and better peak shapes for basic and acidic analytes. Method can be used in analysis of drugs and pharmaceuticals.

Common hydrophobic basic and hydrophilic basic drugs are separated by mixed-mode chromatography with greater selectivity and resolution than traditional reversed-phase column. Drugs are retained by combination of reversed-phase and cation-exchange mechanisms. Retention time is controlled by amount of acetonitrile, buffer concentration and buffer pH. Available detection techniques are based on buffer selection and include UV, Evaporative Light-Scattering Detector (ELSD), Corona (CAD), LC/MS, etc. This HPLC method can be adopted as general approach for analysis of drugs and pharmaceuticals.

Primesep C separates the active ingredients in the over-the-counter cold medicine, NyQuil. Succinate and bromate co-elute early, but acetaminophen, pseudoephedrine, doxylamine, and dextromethorphan are baseline resolved. A combination of cation exchange, complex formation, and hydrophobic interactions separate this mixture with a mobile phase of water, acetonitrile (MeCN, ACN) and triethylamine (TEA) phosphate with UV detection at 205 nm.