Drugs you rub into your skin can be dangerous, too

iStock_000008122420LargeWhen a previously healthy 18-month-old child developed a diaper rash, the toddler’s mother reached for some pain-relieving cream. What she grabbed was a prescription her husband used for neck pain. She rubbed a small amount onto her son’s rash and put him down for a nap.

Within 20 minutes, the child was gasping for breath and unresponsive. An ambulance rushed him to Upstate University Hospital’s pediatric emergency department, where he continued to deteriorate. His heart rate and blood pressure dropped. Doctors inserted a tube in his windpipe to help him breathe.

lessonsThis case was shared in the November issue of the journal, Pediatric Emergency Care. The authors, all health care providers from Upstate, expressed concern that as compound preparations gain popularity, people mistakenly assume they are safer than pills. “This perception and the fact that these are not dispensed in child-proof containers and are often mailed to the patients without pharmacist counseling can lead to increased inadvertent exposures in the pediatric population,” wrote authors, Drs. Ross Sullivan, MD, Michael Holland, MD and Jeanna Marraffa, a doctor of pharmacy at the Upstate Poison Center. Matt Ryzewski, MD was also a co-author; today he is completing a fellowship in neonatal intensive care in Massachusetts.

The skin’s epidermal layer absorbs substances such as pain-relieving cream through diffusion, the speed of which varies depending on the chemical makeup and amount of the substance as well as the condition of the skin.

Poison Center toxicologists Michael Holland, MD, Ross Sullivan, MD, and Jeanna Marraffa, PharmD.

Poison Center toxicologists Michael Holland, MD, Ross Sullivan, MD, and Jeanna Marraffa, PharmD.

The toddler in this case was at particular risk because of his size and his rash. Any open wound on the skin can greatly increase absorption of anything applied to the skin.

“The smaller the child is, the larger the surface area, relative to body weight ratio. As a human grows in volume, so does the surface area, but at a much slower rate,” the authors write. Adults have a small skin surface area-to-weight ratio, compared to infants, who have a large surface area in proportion to size and weight. “Because absorption depends on the amount of surface area exposed to a topical drug, a child will absorb a higher dose per kilogram than an adult.”

The prescription in this case was a compound of several potent drugs known to cause central nervous system depression. Even a small amount was highly toxic to the little boy, who improved over the next 12 hours in intensive care and eventually recovered.

 

Skin is a barrier that exists to keep body water in and microorganisms and noxious chemicals out. The skin consists of three main layers: the epidermis, the dermis and the subcutaneous tissues. The epidermis actually has multiple layers, the most superficial of which is the stratum corneum, which provides almost all the skin’s protective properties. The stratum corneum is made up of keratin, which consists of dead skin cell remnants and fibrous proteins that overlap in layers. Transdermal absorption occurs via a passive diffusion through the epithelial cell layer, in a concentration-dependent process. The magnitude and speed of diffusion depends on the integrity and also physical properties of the applied drug. Drugs with low molecular weight with a high water and lipid solubility show the greatest penetration. Source: “Compounded Ointment Results in Severe Toxicity in a Pediatric Patient,” Pediatric Emergency Care, November 2013

Skin is a barrier that exists to keep body water in and microorganisms and noxious chemicals out. The skin consists of three main layers: the epidermis, the dermis and the subcutaneous tissues. The epidermis actually has multiple layers, the most superficial of which is the stratum corneum, which provides almost all the skin’s protective properties. The stratum corneum is made up of keratin, which consists of dead skin cell remnants and fibrous proteins that overlap in layers. Transdermal absorption occurs via a passive diffusion through the epithelial cell layer, in a concentration-dependent process. The magnitude and speed of diffusion depends on the integrity and also physical properties of the applied drug. Drugs with low molecular weight with a high water and lipid solubility show the greatest penetration.                                                                                          Source: “Compounded Ointment Results in Severe Toxicity in a Pediatric Patient,” Pediatric Emergency Care, November 2013

 

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