Hi Sofia,

G-6-PD is a deficiency of an essential enzyme, glucose-6-phosphate dehydrogenase. This enzyme is important for red blood cell health. Infections, fever, stress, certain foods and drugs may cause a severe hemolytic anemia (red blood cells rupture) when this enzyme is too low or absent. This may cause tea colored urine and yellowing of the skin and eyes. Drugs to avoid in this setting include aspirin, certain antibiotics and a long list of other medications and drugs. Singulair was not on the lists I reviewed.

Phenylketonuria (PKU) is the disease associated with phenylalanine. Children are screened for this disease immediately after birth. There is a problem with converting an amino acid, Phenylalanine, to Tyrosine when a child has PKU. If phenylalanine builds up in the blood, nerve and brain damage may occur. Mental retardation is a risk with high blood levels of phenylalanine. Diet modification is essential in this setting. Kids that have PKU should not have chewable Singulair. The artificial sweetener (Aspartame) in the 4 and 5mg pills of Singulair (chewable) may increase phenylalanine levels and cause severe illness.

The prescribing doctor (regarding the Singulair) should be made aware of your concern.

Get the go-ahead from your doctor before giving Singulair to your child. There are other potential adverse effects that need to be considered related to recent developments about Singulair (discussed on this web site).

I prescribe Singulair to a large number of my patients. I review other medications they are taking, other medical problems and their level of asthma severity or control before writing the prescription.

Again, discuss this with the prescribing doctor before giving the Singulair.

Yours,

J. Thompson, MD