Phentermine clearance is carried out mainly by the kidneys. Therefore, Phentermine excretion time can be considerably slowed down in patients with kidney diseases.
Delayed Phentermine release by the kidneys occurs in chronic renal failure, when patient has reduced blood levels of uric acid, urea and creatinine.
Slower Phentermine excretion is also observed in:
- obstruction of the urinary tract
- violations of protein metabolism in the kidneys
- reduced secretion of the hormone aldosterone
- creatine clearance reduction (less than 30 ml/min).
Slow rate of Phentermine excretion in patients with kidney disease can lead to a sharp increase of the drug concentration in the blood and an increased risk of adverse reactions.
To prevent the increase of Phentermine concentration in plasma and reduce the risk of adverse events, patients with kidney disease are advised to take lower doses of this medication (15 or 18,75 mg per day).
Natural reduction in the glomerular filtration rate is observed in elderly patients, so obese people over the age of 40 should always take Phentermine in minimum therapeutic doses.