Pharmacology · chapter 32 · Weight Management Drugs
Anorexiants
The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.
Key points
Many have been withdrawn
Although these drugs have gone through the standard U.S. Food and Drug Administration (FDA) approval process, many have been removed from the market due to the critical and fatal effects of body stimulation.
Phentermine is short-term
It is recommended for short-term therapy (8–12 weeks) as a daily dose or three times a day before meals.
Phentermine and substance misuse
Phentermine hydrochloride is a Schedule IV controlled substance because there may be a potential for problematic use; it should not be used for clients with a history of substance misuse or substance use disorder.
Who gets phentermine–topiramate
It is utilized in addition to daily caloric restriction and increased physical activity in clients with an initial BMI of 30 kg/m 2 or greater and at least one other comorbidity of hypertension, type 2 diabetes mellitus, and/or dyslipidemia.
Missed dose of phendimetrazine
Nurses should advise clients that if they miss a dose, they should take it as soon as possible; however, if it is close to the time for the next dose, they should skip the dose. Clients should not take double doses.
No MAOIs within 14 days
All four drugs discussed in this section should not be administered within 14 days of taking a monoamine oxidase inhibitor (MAOI), such as phenelzine, selegiline, isocarboxazid, or tranylcypromine.
Phentermine contraindications
The drug is a CNS stimulant, so it is often contraindicated in clients with hyperthyroid conditions, glaucoma, agitation, severe renal impairment, and/or cardiovascular disease such as coronary artery disease, stroke, arrhythmias, congestive heart failure, and uncontrolled hypertension (DailyMed, Adipex-P, 2020).
Stimulant adverse effects
Adverse effects of phentermine are related to the stimulant effects of the drug and include palpitations, tachycardia, arrythmias, precordial pain, nervousness, restlessness, dizziness, insomnia, anxiety, agitation, and tremors.
Not late in the evening
It is important to instruct clients not to take the drug late in the evening because it may cause insomnia.
Seizures after abrupt stop
Life-threatening seizures may occur following abrupt discontinuation of the drug. Clients should be monitored closely for changes in behavior, such as the development of or worsening depression and/or suicidal ideation.
Diabetes and hypoglycemia
Cautious use is recommended in clients with diabetes mellitus because there is a risk of hypoglycemia with weight loss.
Monitor the cardiovascular status
Monitor the client’s cardiovascular status frequently because stimulant effects may alter blood pressure, heart rate, exercise tolerance, and energy levels.
Report these right away
Immediately report shortness of breath, chest pain, dizziness, fainting, or swelling of the extremities.
Tolerance: do not raise the dose
Understand that within a few weeks, tolerance to the appetite-suppressant effects may develop. The client should not increase the dose.
Terms to know
- Anorexiants
- Anorexiants are drugs used to promote weight loss through appetite suppressant and stimulation effects by increasing norepinephrine availability to neural receptors.
- Phentermine hydrochloride
- Phentermine hydrochloride is a sympathetic amine that stimulates the central nervous system to increase norepinephrine (NE) availability.
- Phendimetrazine
- Phendimetrazine is an appetite suppressant used short-term to promote weight loss in conjunction with a low-calorie diet and exercise in clients who did not lose weight with diet and exercise alone.
Practice questions
Stuck on select-all-that-apply? How to take them one option at a time.
The graded version needs JavaScript. Every question is below anyway, with the answer and why.
Every question here, with the answer
A client taking phentermine asks when to take the dose. Which instruction is most appropriate?
- Take it only with a high-fat meal.
- Take it at bedtime so you are not hungry at night.
- Do not take it late in the evening because it may cause insomnia.
- Take a double dose if you feel hungry.
Answer: Do not take it late in the evening because it may cause insomnia.
Phentermine is a stimulant, so clients should not take it late in the evening because it may cause insomnia. Doubling doses is not allowed, and meals are not the way to time it.
A client prescribed phentermine stopped taking phenelzine, an MAOI, five days ago. What should the nurse do?
- Give half the dose.
- Hold the phentermine and contact the provider, because it should not be given within 14 days of an MAOI.
- Give it with food to reduce interaction.
- Give the phentermine as ordered.
Answer: Hold the phentermine and contact the provider, because it should not be given within 14 days of an MAOI.
Anorexiants should not be given within 14 days of an MAOI such as phenelzine because the combination can cause serious effects. Five days is too soon, and reducing the dose or giving food does not remove the risk.
The nurse reviews the history of a client who is asking for phentermine. Which findings are contraindications or reasons to avoid it? Select all that apply.
- History of substance use disorder
- Glaucoma
- Uncontrolled hypertension
- Coronary artery disease
- Seasonal allergies
Answer: History of substance use disorder, Glaucoma, Uncontrolled hypertension, Coronary artery disease
As a CNS stimulant, phentermine is contraindicated in glaucoma and cardiovascular disease including uncontrolled hypertension and coronary artery disease, and it should not be used with a history of substance misuse. Seasonal allergies are not listed.
A client taking phentermine and topiramate ER wants to stop it suddenly. What is the nurse's main concern?
- Life-threatening seizures
- Rebound weight gain within one day
- Hyperglycemia
- Hair loss
Answer: Life-threatening seizures
Abrupt discontinuation of phentermine and topiramate can cause life-threatening seizures, even in clients without a seizure history, so it should be tapered with monitoring. The other options are not the danger described.
A client is going home on an anorexiant. Which symptoms should the nurse teach the client to report immediately? Select all that apply.
- Chest pain
- Fainting
- Reduced appetite
- Shortness of breath
- Swelling of the extremities
Answer: Chest pain, Fainting, Shortness of breath, Swelling of the extremities
Shortness of breath, chest pain, dizziness, fainting and swelling of the extremities must be reported immediately because stimulants can cause critical cardiovascular effects. Reduced appetite is the intended effect.
After three weeks of phentermine, a client says the drug no longer curbs their appetite and plans to take an extra tablet. What should the nurse say?
- Stop the drug suddenly and start a new one.
- Taking an extra tablet is fine if you feel hungry.
- Take it at night instead for a stronger effect.
- Tolerance can develop; do not increase the dose, and notify the prescriber.
Answer: Tolerance can develop; do not increase the dose, and notify the prescriber.
Tolerance to the appetite-suppressant effect may develop within a few weeks; the client should not increase the dose but notify the prescriber. Taking it at night causes insomnia.
Where every quote comes from
Section 32.2 Anorexiants of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.
The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.