Pediatric pharmacist draws inspiration from young patients

Innovators



(from l to r) Student pharmacist Clay Daniels; Hailey Collier, PharmD; student pharmacist Penelope Cronk; Christensen; Katie McCallister, PharmD; and student pharmacist Elizabeth Pickern discuss challenges with pediatric drug formulations.

 

Michael L. Christensen, PharmD, has dedicated his career to helping kids feel better. He divides his time between caring for young patients with parenteral nutrition needs and working as the principal investigator on clinical trials focused on understanding the pharmacokinetics of various medications in pediatric populations.

“The best thing about being in pediatrics is that everyone cares about the children and wants what’s best for them,” said Christensen, Clinical Pharmacy Specialist at Le Bonheur Children’s Hospital in Memphis, TN.

Pediatric research

Christensen began his career in clinical pharmacy more than 30 years ago at Le Bonheur, where he completed a pharmacy residency in 1983. During this time, he was involved in initial studies of the pediatric amino acid solution TrophAmine, which was approved by FDA for infants and children in 1984. Later in his career, Christensen worked on clinical trials that led to specialized pediatric-use language on the product labeling for metformin. 

“We know medicines aren’t ‘one size fits all’ and that we must find better ways to develop and test pharmaceutical formulations designed for children,” said Dennis Black, MD, Director of the Children’s Foundation Research Institute at Le Bonheur. “Christensen and his team have been a tremendous help to the research institute in our efforts to design and conduct clinical studies of drugs for children that will offer safer and more effective options for future pediatric therapeutics.”

Pharmacy expansion

Le Bonheur is a 255-bed facility that values the pharmacist’s role. In 2006, the facility began a 6-year expansion in pharmacy services, growing the pharmacy department from 16 pharmacists and 11 pharmacy technicians to 33 pharmacists and 26 technicians. There are also four postgraduate year (PGY)1 residents, two PGY2 residents, and an active internship program that includes 11 student pharmacists who have the opportunity to work on special projects that have resulted in poster presentations at large pharmacy meetings.

Making a difference



Christensen meets with long-term parenteral nutrition patient, Jalen, to discuss current therapy and gives him a high five for doing well in school.

One of the most rewarding aspects of working with children is developing a deep bond with both a child and his or her parents. Christensen has been taking care of one patient named Jalen since the young man was an infant. During a routine prenatal ultrasound of Jalen’s mother, it was discovered that Jalen’s intestines were outside his abdomen due to a defect in the abdominal wall. When Jalen was born, doctors learned that his intestines had been reabsorbed into the amniotic fluid, which resulted in him having a short gut, with only a very small segment of small intestine and colon remaining. As a result, Jalen, now 11 years, has been on parenteral nutrition his entire life.

Over the years he has been in and out of Le Bonheur with central-line infections and to have his central line replaced. “At one point, his small intestine was the size of a 2-liter bottle of Coke,” said Christensen. Jalen has also undergone two bowel-lengthening procedures. “We had hoped it would increase the absorption enough so he could stop the parenteral nutrition, but nothing has worked so far,” Christensen said. 

At the time of Christensen’s interview with Pharmacy Today, Jalen was back in the hospital with another complication. “He has had so many central lines that a number of blood vessels have clotted off, resulting in superior vena cava syndrome, which causes facial and head swelling,” explained Christensen.

Despite all the health problems, Christensen and Jalen have become good buddies. “It’s fun working with him,” said Christensen. “He tells my pharmacy students that ‘Dr. Mike rules and students drool.’ He’s doing great in school, is academically gifted, and is doing incredibly well in spite of the fact that he’s been tied to parenteral nutrition for his entire life.”

Pharmacokinetic research



Pharmacists Will Maybry and Julie Crowl discuss changes in parenteral nutrition orders with Christensen.

In addition to working with patients, Christensen specializes in developing and conducting clinical trials in children.

After his residency at Le Bonheur, Christensen accepted a fellowship at St. Jude Children’s Research Hospital in 1983 and stayed there for several years as a clinical pharmacist, where he was involved with translational research “years before people started talking about translational research,” he said. 

Christensen came back to Le Bonheur in 1990 and focused his efforts on investigating drugs to see if they are safe and effective in pediatric populations and to establish the proper dose and appropriate interval of medications in young patients.

“One of the biggest challenges in pediatrics is the tremendous difference in size between neonates, infants, older children, and adolescents,” said Christensen. “There could be up to a 100-fold range in just weight.” When coupled with maturational changes that occur in infancy and the metabolic changes that occur around puberty, these factors make designing a study far more complex. “Adult-based study designs just don’t work for infants and children,” he added. 

Clinical hurdles

Another example, noted Christensen, is the triptan drugs such as sumatriptan used in the treatment of migraine headaches. The center did a number of pharmacokinetic studies for this class of drugs, while other centers investigated the safety and efficacy aspects, he noted. “Although our trials showed that the doses in the trials produced concentrations similar to what you see in adults, the safety and efficacy trials did not show that several triptans were more effective than placebo in pediatric patients,” said Christensen. “In fact, about 20% of drugs studied in children have not been shown to be effective.” 

Not all drugs that work in adults are effective in children. Christensen worked on a pharmacokinetic study on pioglitazone, a treatment for adults with type 2 diabetes. He helped design the study and assisted with enrolling approximately one-third of the study participants. “It turns out that pioglitazone is one of those drugs that has not been shown to be safe and effective in children,” he said. “The study’s sponsor decided not to pursue testing in children because of some of the toxicities seen in adults.”

One of the biggest challenges of doing studies with a pediatric population is the need to involve parents as well as children. “Often you need to get consent from both parents and assent from the child, or there might be logistical issues with siblings, so in many cases you are dealing with the entire family,” explained Christensen. 


 
Brandon Edgerson, PharmD, and Michael Christen, PharmD, discuss how the addition of the drug carousel to the main pharmacy is improving medication safety.

Current research

Numerous pediatric research projects are underway at Le Bonheur on both the outpatient and inpatient side for diseases such as cystic fibrosis, diabetes, and epilepsy.

Christensen’s next project is focused on learning whether pediatric-specific language on drug labels influences prescribing patterns for those drugs in children. He is hoping to embark on a series of studies that examine prescribing before and after pediatric information is incorporated into product labels indicating that drugs have not been found effective in children.

Christensen is most proud of developing the pediatric clinical research unit at Le Bonheur as a resource for conducting studies needed to get drugs approved for use in children. “The program started with very modest beginnings and now occupies half of one floor at the hospital and has an outstanding infrastructure of research nurses, informaticists, and biostatisticians to support investigators interested in pediatric research,” said Christensen. “In the end, it is all about the children, whether demonstrating that drugs are safe and effective or taking care of a child who has required parenteral nutrition all their life.”