Aislinn Antrim, Associate Editor

Although antihistamines are commonly used to manage hives, sneezing, and watery eyes during allergy season, many patients may be taking their medications incorrectly, according to Derek Chu, MD, PhD, a McMaster University allergy expert and clinical scholar.

“People need to rethink what they stock in their home cabinets as allergy medicines, what hospitals keep on formulary, and what policymakers recommend,” Chu said in a press release. “The message needs to get out. This publication is on time for the spring allergy season and as COVID vaccines roll out, for which rashes are common and antihistamines can be helpful.”

Co-author Gordon Sussman, MD, FRCP, FACP, DIP.ABIM, FAAAAI, said in the press release that there are new second generation antihistamines that prescribers should know about. Their new study, published in the 

, lists 5 things to know about proper antihistamine use.

Antihistamines are among the most commonly and incorrectly used medications worldwide, according to the press release. Their best use is for the management of hay fever and outbreaks of hives, and not for management of asthma, eczema, coughs, or insomnia.

Notably, first-generation antihistamines are associated with substantial and sometimes fatal adverse effects (AEs). These antihistamines are ones with diphenhydramine, chlorpheniramine, or hydroxyzine, which can cause drowsiness and affect cognitive functions, such as school performance. Overdosing with these types of antihistamines can cause death and are potentially dangerous for both young and older people.

Second-generation antihistamines are safer and just as affordable and as effective as first-generation antihistamines, according to the study authors. Later-generation antihistamines are proven to be more effective and last longer with less severe AEs, such as drowsiness, according to the study authors.

In their fourth point, the authors said antihistamines should not be used instead of epinephrine to treat anaphylaxis. Oral drugs can be used in combination with epinephrine injections to treat anaphylactic reactions, but they are not a proper substitute.

Finally, they said most antihistamines are safe to use during pregnancy and breastfeeding. Researchers have shown that antihistamines at standard doses do not harm fetuses during pregnancy and may be used during breastfeeding. Similarly, the researchers said they are safe for children to use.

“These are new modern second-generation antihistamines that are potent, specific, fast acting, and of proven safety which everyone should be using to treat allergic rhinitis and hives,” Sussman said in the press release.

Are you using antihistamines properly? [news release]. EurekAlert; April 6, 2021. 

https://www.eurekalert.org/pub_releases/2021-04/mu-ayu040121.php

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Second-generation antihistamines are safer and just as affordable and as effective as first-generation antihistamines, according to the study authors.

Note Proper Use of Antihistamines During Spring Allergy Season

In addition to the usual considerations of treating pediatric patients, clinicians should consider how pharmacokinetics may differ for children with obesity, according to a session at the 2021 virtual National Association of Pediatric Nurse Practitioners meeting.

The CDC defines obesity in children as weight at the ninety-fifth percentile or above, according to presenter Heather Herrera, RN, MSN, CPNP-AC/PC. For children between 2 and 19 years of age, this amounts to 18.5% or approximately 13.7 million obese children and adolescents. Furthermore, Herrera said is it estimated that approximately 20% of admissions to children’s hospitals involve children with obesity.

Obesity in pediatric populations has both long- and short-term implications and affects every single body system, Herrera said. Psychosocial impacts can include low self-esteem, depression, and eating disorders. Cardiovascular impacts can include dyslipidemia, hypertension, chronic inflammation, and endothelial dysfunction, while endocrine impacts include type 2 diabetes and precocious puberty.

Obesity in children also causes changes in physiology, such as changes in tissue composition, larger amounts of both fat body mass and lean body mass, and impaired liver and kidney function. Herrera noted that obese adults have shown increased blood volume, cardiac output, and renal blood flow.

When considering pharmacokinetics, Herrera said understanding volume of distribution (Vd) and clearance is essential. Vd is a theoretical parameter correlated to the total amount of drug distributed in the body and the resulting plasma level, which then determines the loading dose. It is the outcome measure most affected by obesity and it is determined mostly by the physiochemical properties of the drug and is specific to each individual, although it may vary in physiological and pathological conditions.

There are several body measurements to be considered, and each has its own uses and situations in which it is the most helpful. Ideal body weight (IBW) is a weight believed to be maximally healthful, based chiefly on height but modified by factors such as gender, age, and build. Total body weight (TBW) is a measure of mass in kilograms or pounds, whereas lean body weight (LBW) is the amount of weight that isn’t fat. Finally, adjusted body weight reflects lean body mass plus excess fat mass determined by a cofactor, and is a measurement mostly used in adults.

Notably, despite these options, Herrera said there is no gold standard for how to calculate IBW in children. For children taller than 5 feet, Herrera recommended the calculation (2.27 x [height in inches -60]) plus 42 for girls and plus 39 for boys. For children shorter than 5 feet, the formula is ([height in inches]2 x 1.65/1000).

When considering pharmacological challenges, it is important to identify correct dose of medication at the onset of therapy, particularly in critically ill children who need quick improvement. Notably, inadequate dosing can lead to treatment failure and adverse events.

In obese children, Herrera said volume of distribution and clearance are best represented by TBW and LBW, and these measurements are often used to determine dosage of a medication. The degree of lipophilicity and hydrophilicity should also be considered, as well as differences in loading versus maintenance dosing. Loading doses of hydrophilic medications in obese children should be based on IBW, whereas partially hydrophilic and lipophilic medications should be based on TBW.

Finally, Herrera reviewed common medication classes and various considerations in children with obesity. Obese children seem to require less heparin, enoxaparin, and warfarin per kilogram TBW than non-obese children, and may also require less vancomycin and aminoglycosides per kilogram.

By carefully considering pharmacokinetics and physiologic changes in children with obesity, clinicians can prescribe proper dosages and treatments for children, whether in mild conditions such as allergies or in more critical care cases.

Herrera H, and Joiner J. Bigger is not always better: Pediatric obesity and its implications for critical care with case study discussions. NAPNAP 2021; March 27, 2021. 

https://napnap21.org/community/#/session-stream/42198

In addition to the usual considerations of treating pediatric patients, clinicians should consider how pharmacokinetics may differ for children with obesity, according to a session at the 2021 virtual National Association of Pediatric Nurse Practitioners meeting. 

Clinicians Should Consider How Obesity Affects Pharmacokinetics in Children 

With 3 FDA-approved COVID-19 vaccines and other potential candidates in the pipeline, addressing patients’ concerns and questions about the vaccines requires up-to-date information and careful review.

A session at the National Association of Pediatric Nurse Practitioners (NAPNAP) 2021 National Conference on Pediatric Health Care reviewed the latest information on COVID-19 vaccines. Presenter Dana DeShon, CNP, said that although the development process for COVID-19 vaccines has been accelerated, it is important to reassure patients that there were no shortcuts for safety and efficacy.

In addition to the Pfizer and BioNTech, Moderna, and Johnson & Johnson vaccines, which have received FDA approval, DeShon said there were 223 candidate vaccines as of December 2020, including 57 clinical phase vaccines and 166 pre-clinical phase vaccines. She explained that after vaccine candidates receive approval for testing in humans, they go through 4 phases. Phases 1 through 3 are conducted prior to FDA review, with increasing numbers of participants. Phase 4 is conducted after FDA review and involves 1000 or more participants.

Following this general review, DeShon explained the various approaches to vaccine development, such as DNA, non-replicating viral vectors, or purified protein.

The DNA approach to vaccine development involves getting DNA into the nucleus of the cell. A vaccine candidate by Inovio Pharmaceuticals uses this approach, with a phase 1 trial that began in April 2020 and a phase 2/3 trial that launched in November 2020. This vaccine requires 2 doses and is stable at room temperature for more than a year, with a 5-year projected shelf life at normal refrigeration temperatures. When counseling patients on DNA vaccines, DeShon said it is important to note that they enter the cell but do not change the recipient’s own DNA.

The Johnson & Johnson vaccine is an example of a non-replicating vital vector vaccine, which originates from a carrier virus, such as the adenovirus or pox virus. DeShon said a gene is inserted into a vector virus to code it, and it is important to note that the virus vector does not reproduce in the vaccine recipient.

The immune system then creates antibodies against proteins such as the COVID-19 spike protein, and antibodies directed against the spike protein will prevent COVID-19 from binding to the cell and thus prevent infection. In these vaccines, DeShon said the only concern could be if a patient had previous exposure to COVID-19, which could negatively impact the body’s response.

The vaccines from Pfizer/BioNTech and Moderna are both messenger ribonucleic acid (mRNA) vaccines. This approach is composed of a piece of the virus’s genetic code surrounded by lipids. Notably, it does not interact with DNA and patients cannot get COVID-19 from the vaccine.

The Pfizer and BioNTech vaccine demonstrated 95% efficacy against COVID-19 in a clinical trial of 43,448 participants, 21,720 of whom received the vaccine and 21,728 of whom received a placebo. Investigators observed 170 cases of COVID-19 with onset at least 7 days after the second dose, 162 of whom were in patients who received the placebo. They also found a response beginning 12 days after the first dose and 7 days after the second dose.

Notably, the Pfizer and BioNTech vaccine is the only one to be approved for individuals aged 16 years and older, as Moderna and Johnson & Johnson are approved for 18 years of age and older. The FDA approved the Pfizer/BioNTech vaccine in October to begin clinical trials in patients as young as 12 years of age.

Moderna’s vaccine is also an mRNA vaccine. In a clinical trial with 27,817 participants, 11 cases of COVID-19 were reported in the vaccinated group and 185 cases were reported in the placebo group as of November 21, 2020. Notably, there were no severe cases in the vaccinated group. Researchers found 80.2% protection 2 weeks after the first dose and 94.1% protection after the second dose.

DeShon said that safety monitoring for the mRNA vaccines did see some cases of anaphylaxis. Of patients who experienced this, 86% had onset within 30 minutes of vaccination and 81% had a history of allergies or allergic reactions. The most common adverse reactions include injection site pain, fatigue, headache, muscle pain, joint pain, and chills.

For patients who have concerns about vaccine safety and adverse effects, DeShon said clinicians have several options to bolster trust. Telling personal stories about receiving the vaccine and using a direct, fact-based approach can both answer their questions and demonstrate safety.

DeShon, Dana. COVID-19 Vaccine. National Association of Pediatric Nurse Practitioners; March 26, 2021. Virtual; Accessed March 26, 2021.

Telling personal stories about receiving the vaccine and using a direct, fact-based approach can both answer patient’s questions and demonstrate safety when advising them on COVID-19 vaccines.

Practitioners Should Have Updated Information to Advise Patients on COVID-19 Vaccines

The CDC has released new guidance for individuals who have been fully vaccinated against COVID-19, saying that they can safely gather with other fully vaccinated people or with unvaccinated people who are at low risk for severe COVID-19.

Although the guidelines still urge vaccinated individuals to wear masks and continue to remain physically distanced in public spaces, the CDC said that vaccinated people can safely visit with others who are vaccinated indoors without wearing masks or physical distancing. When visiting those who are unvaccinated, the guidelines state that vaccinated individuals can visit those from a single household who are at low risk for severe COVID-19 without masks or physical distancing.

Notably, the guidelines also said vaccinated individuals can refrain from quarantining and testing following a known COVID-19 exposure if they are asymptomatic. Regardless of vaccination status, however, those with symptoms consistent with COVID-19 should isolate from others and get tested if indicated.

The guidance said relaxing certain measures for vaccinated individuals may help improve vaccine acceptance and uptake. According to the CDC, individuals are considered fully vaccinated 2 weeks after they have received the second dose in a 2-dose series or 2 weeks after receiving a single-dose vaccine. Indoor visits in which everyone is fully vaccinated present a low risk. For this reason, the guidance said masks and physical distancing are not necessary in small, fully vaccinated groups.

Visits and small gatherings likely pose minimal risk to fully vaccinated people, the guidance said, although larger groups and those including unvaccinated people from multiple households increase the risk of COVID-19 transmission. Vaccinated people should still be mindful of potentially spreading the virus to others, especially those who are unvaccinated or at increased risk for severe illness from COVID-19.

Because vaccinated individuals are likely at low risk, the guidelines said the level of precautions taken should be determined by the characteristics of the unvaccinated people. For example, masks should still be worn around older adults or those at high risk of severe COVID-19, and physical distancing should still be maintained. Notably, everyone in the group should take these precautions, including those who are fully vaccinated.

Risks during other activities outside the home, such as eating at a restaurant or going to the gym, are also lower for vaccinated individuals. However, the guidelines said precautions should still be taken to prevent transmission of COVID-19 to unvaccinated individuals. These precautions include wearing a well-fitting mask, maintaining at least 6 feet of space between people, avoiding crowds, avoiding poorly ventilated spaces, covering coughs and sneezes, and washing hands frequently.

Interim Public Health Recommendations for Fully Vaccinated People. CDC; Updated March 8, 2021. 

https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated-guidance.html

The guidance said relaxing certain measures for vaccinated individuals may help improve COVID-19 vaccine acceptance and uptake.

Aislinn Antrim, Associate Editor

Articles

Note Proper Use of Antihistamines During Spring Allergy Season

Clinicians Should Consider How Obesity Affects Pharmacokinetics in Children

Practitioners Should Have Updated Information to Advise Patients on COVID-19 Vaccines

CDC Guidance Says Individuals Fully Vaccinated Against COVID-19 Can Safely Gather Indoors Without Masks, Physical Distancing