The human brain controls your body by orchestrating the highly complex and delicate interaction between neurons, neurotransmitters, hormones and electrical signals. Natural and man-made substances can impact this balancing act. Dietary supplements such as melatonin act on natural brain mechanisms that allow you to sleep. The drug Seroquel acts by blocking the effects of natural neurotransmitters. Any two substances -- whether natural or artificial -- taken together may interact with each other with negative consequences on the brain and other parts of the body. Always consult your physician before you combine melatonin or any dietary supplement with a prescription drug.
Melatonin is a hormone -- a naturally occurring substance that helps regulate the normal functioning of the body. Most of the body's supply of melatonin is produced and released by the brain's pineal gland. Melatonin helps you maintain normal wake and sleep cycles and taking it in supplement form can help you fall asleep faster. The body makes its melatonin using the amino acid tryptophan as an ingredient. Melatonin helps promote sleep by triggering receptors in the brain designed especially for it.
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Seroquel is the brand name for the prescription anti-psychotic drug quetiapine. It is prescribed for the treatment of schizophrenia, a severe mental disorder that makes it hard to tell if what you are experiencing is real or not. While the exact causes of schizophrenia are unknown, drugs like Seroquel work by blocking the effect of the neurotransmitters dopamine and serotonin in the brain. Seroquel also is used to balance moods in patients with bipolar depression and mania.
Seroquel Drug Interactions
The list of drugs that Seroquel interacts with is long and broad. Serorquel's list of negative side effects is even longer. The prescribing information for Seroquel lists drug interactions with phenytoin, carbamazepine, barbiturates, rifampin, glucocorticoids, divalproex, thioridazine, cimetidine, ketoconazole, itraconazole, fluconazole, erythromycin, protease inhibitors, lorazepam and lithium. The majority of these interactions involve the way the body gets rid of Seroquel and other drugs. The enzyme cytochrome P450 3A plays a major role in removing Seroquel from the body. Some drugs inhibit this enzyme and cause Seroquel levels to remain high in between doses. Increased drowsiness, dizziness, cognitive and motor impairment may result. Seroquel's side effects can even be deadly, especially in older adults.
Melatonin and Seroquel
No studies to date document any drug interactions between Seroquel and melatonin. A 2009 review of melatonin drug interactions published in "Natural Medicine Journal," did not mention quetiapine as a potential risk. AstraZeneca, the makers of Seroquel, do not mention melatonin in the drug's prescribing information. Melatonin is not a CYP4503A inhibitor. Seroquel's blocking effect of serotonin does not interfere with melatonin's function or disposition in the body. Both Seroquel and melatonin have sedative effects. Caution should be taken if the two are taken together. Increased sluggishness, drowsiness or dullness of mind may put you at risk of injury due to falls or accidents from driving or operating dangerous equipment.
- "The British Journal of Psychiatry": Management of insomnia: treatments and mechanisms; Sue Wilson, PhD et al.; 2007
- "MedlinePlus": Melatonin; December 3, 2010
- "Journal of Psychopharmacology": British Association for Psychopharmacology consensus statement on evidence-based treatment of insomnia, parasomnias and circadian rhythm disorders; SJ Wilson, et al.; September 2, 2010
- "Psycheducation.org": quetiapine (Seroquel)
- "Journal of Clinical Sleep Medicine": Insomnia: Definition, ; Thomas Roth; August 15, 2007