The impact of oral phenylpropanolamine on blood pressure: a meta-analysis and review of the literature.

ABSTRACT

Oral phenylpropanolamine is commonly used to treat congestion and obesity. Clinicians often wonder what effect it has on blood pressure and whether they are safe in hypertensive patients. The purpose of our systematic review was to assess whether these drugs cause clinically meaningful elevations in pulse or blood pressure. English-language, randomized, placebo-controlled trials of oral phenylpropanolamine in adults with extractable data on pulse or blood pressure were studied. MEDLINE (1966-2003), Embase, the Cochrane library and reviewed article references were used as sources. Systolic (SBP) and diastolic blood pressure (DBP) and heart rate data were extracted. Additional extracted data included demographics, year, study design, study duration, drug dose and frequency, duration of washout and country. Study quality was assessed using the methods of Jadad and data were synthesized using a random effects model using weighted mean differences. In all, 33 trials reporting 48 treatment arms with 2165 patients were included. Phenylpropanolamine increased SBP 5.5 mmHg (95% CI 3.1-8.0) and DBP 4.1 mmHg (95% CI 2.2-6.0) with no effect on pulse. Patients with controlled hypertension were not at greater risk of blood pressure elevation. Immediate release preparations had greater effects on blood pressure than sustained release ones. Higher doses and shorter duration use also caused greater increases. Eighteen studies contained at least one treated subjects having blood pressure elevations > or =140/90 mmHg, an increase in SBP > or =15 mmHg or an increase in DBP > or =10 mmHg. In conclusion, phenylpropanolamine caused a small, but significant increase in systolic blood pressure. The effect was more pronounced with shorter-term administration, higher doses of medication and immediate release formulations.