Propylhexedrine, sold under the brand name Benzedrex, is a nasal decongestant, appetite suppressant, and psychostimulant medication. It is used medicinally for relief of congestion due to colds, allergies and allergic rhinitis. Propylhexedrine is most commonly found in over-the-counter Benzedrex inhalers. Benzedrex was first manufactured by Smith, Kline and French after the Benzedrine inhaler, which contained racemic amphetamine, became unavailable following the placement of amphetamines on the US Schedule II status (highest abuse potential, yet with accepted medicinal uses). Benzedrex is currently manufactured by B.F. Ascher & Co. Inc. Pharmaceuticals. Propylhexedrine has also seen use in Europe as an appetite suppressant, under the trade name Obesin. Additionally, it is found in the anticonvulsant preparation barbexaclone, where its S-isomer (levopropylhexedrine or L-propylhexedrine) is bonded with phenobarbital for the purpose of offsetting the barbiturate-induced sedation. Levopropylhexedrine is also used as an anorectic, under the brand name Eventin. Medical use Propylhexedrine is used to treat acute nasal congestion related to common cold, allergies and hay fever. For nasal congestion, the dosage is listed as four inhalations (two inhalations per nostril) every two hours for adults and children 6–12 years of age. Each inhalation delivers 0.4 to 0.5 milligram (400 to 500 μg) in 800 millilitres of air. Historically, it has also been used for weight loss, typically at doses from 5 to 30 milligrams. Contraindications Propylhexedrine should not be used if a MAOI has been used in the past 14 days or is currently in use, as this can result in hypertensive crisis. People with cardiovascular disease should not use propylhexedrine. Additionally, stimulant drugs and sympathomimetics should not be taken with propylhexedrine, as this can lead to a potentially dangerous spike in blood pressure and irregular heart rhythms. There is one case of death where a combination of propylhexedrine, acetaminophen, morphine, promethazine, and kratom was detected. However, the study indicates that propylhexedrine was most likely the principal cause. Pharmacology Propylhexedrine is a TAAR1 agonist, like amphetamine. Consequently, it reverses the transporters for dopamine, norepinephrine, and serotonin, leading to a release of monoamines from presynaptic vesicles into the synaptic cleft. The increased level of monoamines within the synapse results in increased activity at their respective receptors. Additionally, propylhexedrine appears to inhibit VMAT2, leading to a further increase in the aforementioned monoamines. The pharmacological actions of propylhexedrine are similar to that of structurally similar stimulant phenethylamines, such as amphetamine. Metabolism Propylhexedrine undergoes metabolism to form various