What are the considerations for prescribing Lomaira (phentermine) to a patient for weight loss?

Lomaira (Phentermine 8mg) Prescribing Considerations

Lomaira is FDA-approved low-dose phentermine (8mg up to three times daily) for short-term obesity treatment in patients with BMI ≥30 kg/m² or ≥27 kg/m² with comorbidities, but should only be prescribed to younger patients without cardiovascular disease, uncontrolled hypertension, anxiety, or insomnia, with mandatory blood pressure and heart rate monitoring at every visit. 1, 2

Patient Selection Criteria

Appropriate Candidates

• Patients with obesity (BMI ≥30 kg/m² or ≥27 kg/m² with risk factors like controlled hypertension, diabetes, or hyperlipidemia) who need appetite suppression assistance 1, 2
• Younger patients without cardiovascular disease or uncontrolled hypertension are preferred candidates 1
• Patients who can tolerate sympathomimetic stimulation without worsening anxiety or insomnia 1

Absolute Contraindications (Do Not Prescribe)

• Any history of cardiovascular disease including coronary artery disease, stroke, arrhythmias, congestive heart failure, or uncontrolled hypertension 3, 2
• Current or recent (within 14 days) monoamine oxidase inhibitor use 1, 2
• Hyperthyroidism 4, 2
• Glaucoma 4, 2
• Agitated states or significant anxiety disorders 4, 2
• History of drug abuse 2
• Pregnancy or nursing 1, 2
• Known hypersensitivity to sympathomimetic amines 2

Relative Contraindications (Use Extreme Caution)

• Even mild uncontrolled hypertension requires careful consideration 3, 2
• Patients with anxiety or insomnia may experience exacerbation 1
• Severe renal impairment (eGFR 15-29 mL/min/1.73m²) requires dose limitation to 15mg daily maximum 2
• End-stage renal disease or dialysis patients should avoid phentermine entirely 2

Pre-Treatment Assessment Requirements

Mandatory Screening

• Obtain baseline blood pressure and heart rate measurements 4, 3
• Screen for any history of coronary artery disease, stroke, arrhythmias, heart failure, or uncontrolled hypertension 4, 3
• Assess pregnancy status in all women of reproductive potential (phentermine is contraindicated in pregnancy) 1, 4
• Exclude hyperthyroidism 4, 2
• Exclude glaucoma 4, 2
• Screen for agitated states or anxiety disorders 4, 2
• Verify no current or recent (within 14 days) MAOI use 4, 2
• Assess renal function 4, 2

Dosing and Administration

Lomaira-Specific Dosing

• Lomaira is available as 8mg scored tablets that can be prescribed up to three times per day 1
• This low-dose formulation received FDA approval in September 2016 1

Standard Phentermine Dosing

• Traditional phentermine dosing is 15-37.5mg orally once daily in the morning 1
• Avoid late evening administration due to risk of insomnia 5, 2
• Phentermine can be taken with or without food (absorption not significantly affected) 4, 2
• For severe renal impairment (eGFR 15-29 mL/min/1.73m²), limit dosage to 15mg daily 2

Monitoring Requirements

Ongoing Surveillance

• Monitor blood pressure and heart rate at every visit throughout treatment 4, 5, 3
• Assess efficacy and safety at least monthly 3
• Discontinue if less than 5% weight loss after 12 weeks on maximum dose 4, 5
• For women of reproductive potential, provide pregnancy counseling and potentially monthly pregnancy testing 4

Cardiovascular Monitoring Rationale

• Phentermine causes mild increases in heart rate (typically 5-10 beats per minute) and blood pressure through sympathetic nervous system activation 1, 5
• Consider dose reduction or discontinuation if blood pressure or heart rate becomes uncontrolled 5

Expected Treatment Outcomes

Efficacy Data

• In a 28-week randomized controlled trial, phentermine 15mg daily produced 6.0kg weight loss compared to placebo 1
• 46% of patients achieved ≥5% weight loss and 20.8% achieved ≥10% weight loss 1, 3
• When combined with lifestyle interventions, phentermine can achieve 5-10% body weight loss in successful patients 1, 3

Duration of Treatment

FDA-Approved Duration

• Phentermine is FDA-approved only for short-term use (3 months) due to lack of long-term safety trials 1, 4, 2

Off-Label Extended Use

• Many practitioners prescribe phentermine for longer durations (3-6 months or more) in off-label fashion because obesity is a chronic metabolic disease requiring long-term management 4, 3
• If prescribing beyond 12 weeks, document specific benefits, tolerance profile, adverse effects, and counsel patients regarding off-label use and limited long-term safety data 4
• Blood pressure and heart rate monitoring at every visit remains mandatory for extended use 4, 5

Common Side Effects and Management

Frequent Side Effects

• Dry mouth (manage with adequate hydration) 1, 5
• Difficulty sleeping/insomnia (minimize by avoiding late evening dosing) 1, 5
• Dizziness 1
• Irritability and anxiety 1, 5
• Headache 5
• Constipation (manage with fiber supplement and adequate hydration) 5
• Palpitations 5

Serious Adverse Effects Requiring Immediate Discontinuation

• Dyspnea (shortness of breath) may indicate cardiovascular compromise or primary pulmonary hypertension 5, 2
• Angina pectoris suggesting cardiac ischemia 5, 2
• Syncope requiring urgent evaluation 5, 2
• Severe hypertension or hypertensive crisis 5, 2
• Arrhythmias 5, 2
• New unexplained lower extremity edema 2

Drug Interactions

Dangerous Interactions

• Monoamine oxidase inhibitors: Risk of hypertensive crisis (contraindicated during or within 14 days of MAOI use) 1, 2
• Other sympathomimetic amines should not be used concurrently 1, 2

Important Interactions

• Alcohol: Consider potential adverse drug reaction 2
• Insulin and oral hypoglycemics: Requirements may be altered; dose reduction may be necessary 2
• Adrenergic neuron blocking drugs: Hypotensive effect may be decreased by phentermine 2

Alternative Weight Loss Medications

When Cardiovascular Risk Precludes Phentermine

• Orlistat (lipase inhibitor) is a safer alternative for patients with cardiovascular concerns as it works by blocking absorption of approximately 30% of ingested fat rather than affecting the sympathetic nervous system 1, 4, 3
• Orlistat is available as prescription (Xenical 120mg three times daily) or over-the-counter (Alli 60mg) 1, 4

Superior Efficacy Options

• GLP-1 receptor agonists (semaglutide 2.4mg or liraglutide 3.0mg) offer superior efficacy with different safety profiles and may be preferred for severe obesity 4, 3
• These agents do not carry the cardiovascular risks associated with sympathomimetic agents 4

Critical Pitfalls to Avoid

Common Prescribing Errors

• Do not confuse phentermine monotherapy with the discontinued "fen-phen" combination (phentermine-fenfluramine) 4
• The cardiovascular risks (valvular heart disease and pulmonary hypertension) associated with fen-phen were attributed to fenfluramine, not phentermine 4
• Never prescribe phentermine to patients with any cardiovascular disease, even if well-controlled 3, 2
• Do not combine phentermine with other weight loss medications without clear evidence of safety 2
• Do not exceed recommended doses if tolerance develops; instead, discontinue the medication 2

Abuse Potential Considerations

• Phentermine is a Schedule IV controlled substance 1
• Prescribe or dispense the least amount feasible at one time to minimize possibility of overdosage 2
• Recent research suggests no data supports the notion that phentermine is addictive in clinical practice 6

Patient Counseling Points

Essential Information to Communicate

• Phentermine is FDA-approved only for short-term use (3 months), though off-label longer duration is common in clinical practice 4
• The goal is 5-10% body-weight loss in the majority of successful patients, not dramatic weight loss 1
• Obesity is a chronic disease requiring long-term treatment with multiple approaches utilized simultaneously 1
• Common side effects include dry mouth, difficulty sleeping, dizziness, and irritability 1
• Report immediately any chest pain, shortness of breath, fainting, or severe headache 5, 2
• Avoid late evening dosing to minimize insomnia 5, 2
• Women of reproductive potential must use effective contraception (phentermine is contraindicated in pregnancy) 1, 4