FDA Approvals: Adderall XR for Adults, Topamax for Migraines, and Others

Yael Waknine

August 19, 2004

Aug. 19, 2004 — The U.S. Food and Drug Administration (FDA) has approved mixed salts of a single-entity amphetamine for use in adults with attention deficit hyperactivity disorder, topiramate for migraine prophylaxis in adults, a new algorithm to improve distribution of radiation therapy in heterogenous body areas, and two drugs to treat internal contamination from radioactive elements.

Mixed Salts of a Single-Entity Amphetamine (Adderall XR) for Adults With ADHD

On Aug. 11, the FDA expanded the indication for amphetamine aspartate/amphetamine sulfate/dextroamphetamine saccharate/dextroamphetamine sulfate (Adderall XR, made by Shire Pharmaceuticals Group plc), allowing its use as a once-daily treatment for adults with attention deficit hyperactivity disorder (ADHD).

According to a company news release, studies have shown that up to 65% of children with ADHD continue to exhibit symptoms into adulthood. If left untreated, the disorder can lead to other psychological difficulties, such as depression and occupational and social disability.

The amphetamine combination was approved for use in children with ADHD in November 2001.

Topiramate (Topamax) for Migraine Prophylaxis

On Aug. 11, the FDA approved a new indication for topiramate tablets and sprinkle capsules (Topamax, made by Ortho-McNeil Pharmaceutical, Inc.), allowing their use for migraine prophylaxis in adults.

The approval was based on results of clinical trials showing that daily use of topiramate at the recommended dose significantly decreased the number of monthly migraine attacks in about 50% of patients compared with placebo.

Topiramate was previously indicated as adjunctive therapy for adult and pediatric patients aged two to 16 years with partial onset seizures or primary generalized tonic-clonic seizures, and in patients aged two years and older having seizures associated with Lennox-Gastaut syndrome.

Algorithm (AAA) Improves Radiation Dose Distribution to Tumors in Heterogenous Areas of Body

On Aug. 2, the FDA approved a new dose calculation algorithm (AAA, made by Varian Medical Systems) for use with the company's Eclipse 3D radiotherapy treatment planning software.

The AAA algorithm improves distribution of radiation doses to tumors in areas surrounded by heterogenous tissue, such as the lung, by accounting for electron scatter and dose effects resulting from interaction of the radiation with different tissues and air pockets.

According to a company news release, use of the algorithm with Eclipse 3D software can produce a treatment plan for a large tumor in less than a minute.

Pentetate Calcium Trisodium (Ca-DTPA) and Pentetate Zinc Trisodium (Zn-DTPA) Injections for Radiation Contamination

On Aug. 11, the FDA approved pentetate calcium trisodium (Ca-DTPA) and pentetate zinc trisodium (Zn-DTPA) injections, made by Hameln Pharmaceuticals, GmbH) for the treatment of internal contamination with the radioactive elements plutonium, americium, or curium.

The radioactive elements may be released from laboratory or industrial accidents or in a terrorist "dirty bomb" attack using a radiation dispersal device. Routes of contamination include ingestion, inhalation, or direct wound contact.

The new injections increase the rate of elimination of plutonium, americium, and curium from the body, thus decreasing risk of possible future effects such as cancer.

Pentetate calcium trisodium and pentetate zinc trisodium should not be administered simultaneously. Pentetate calcium trisodium should be administered first due to its higher effectiveness during the first 24 hours of internal contamination. Further doses if needed may be of either drug because they demonstrate similar effectiveness after 24 hours.

Themain adverse effect of pentetate calcium trisodium involves the loss of replaceable essential nutritional metals such as zinc, which occurs to a lesser degree with pentetate zinc trisodium.

In patients with inhalation contamination only, these drugs may also be administered by nebulized inhalation. This may result in breathing difficulties for some individuals.

Pentetate calcium trisodium and pentetate zinc trisodium injections have been investigational drugs for several decades, indicated in the treatment of patients in radiation contamination emergencies.

Reviewed by Gary D. Vogin, MD

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