Analysis of Mannitol in Human Plasma

Mannitol is an osmotic diuretic that is physiologically inactive in humans and is found naturally in fruits and vegetables as a sugar or sugar alcohol. Mannitol raises the osmolality of blood plasma, allowing more water to move from tissues including the brain and cerebrospinal fluid into interstitial fluid and plasma (1).

analysis of mannitol in human plasma

Fig.1 3D Model of Mannitol

Mannitol can be used to:

  • Reduce Inter-cranial Pressure

Mannitol is administered intravenously and becomes a new solute in the plasma. Thus, increasing the tonicity of the plasma, which will pull water into the intravascular space from the brain parenchyma. The water will then be excreted through the kidneys.

  • Reduce Intra-ocular Pressure

Due to an increase in the plasma's tonicity by mannitol, water from the vitreous humous of the eye is drawn out to the intravascular space.  Finally, the water and mannitol will be excreted by the kidneys. The intraocular pressure is reduced as the vitreous humor’s water content decreases.

  • Promote Diuresis in Acute Renal Failure

Intravenous mannitol is sometimes given to those who have acute renal failure. Even in acute renal failure, the kidneys are responsible for a large portion of mannitol excretion. As mannitol is expelled, it attracts water, boosting the patient’s water output and assisting in the prevention or treatment of fluid overload caused by oliguria in acute renal failure.

  • Excrete Toxic Materials

Mannitol can be used to promote the excretion of harmful chemicals, substances, and medications, similar to how it is used to treat oliguria in acute renal failure.

  • Prevent Intradyalytic Hypotension

Hemodialysis patients frequently experience intradialytic hypotension and dialysis disequilibrium symptoms. The reason for this is a decrease in intradialytic osmolality. By increasing serum osmolality, mannitol can help prevent intradialytic hypotension.


Mannitol is administered intravenously when used for medical purposes (2). Mannitol
is available in a variety of quantities, ranging from 5% mannitol (5 gm mannitol
dissolved in 100 mL solution) to 25% mannitol (25 gm of mannitol dissolved in 100 mL
of fluid) (2). The amount of mannitol administered depends on the type of condition
that is being treated (2).

  • Increased Intercranial Pressure – dosages range from 0.25 g/kg to 2 g/kg
  • Increased Intraocular Pressure – dosages range from 0.25 g/kg to 2g/kg
  • Oliguria treatment – 0.2 g/kg
  • Excretion of toxic materials – 0.25 g/kg to 2 g/kg

Side effects

  • Heart failure
  • The movement of free water into the intravascular region might cause or worsen electrolyte imbalances. Hyponatremia, hypokalemia, and hypocalcemia are some of the electrolyte disorders that might occur.
  • Worsen cerebral edema. Frequent mannitol doses can cause mannitol to penetrate the blood-brain barrier, worsening cerebral edema because the mannitol that has leeched into the brain attracts water into the brain rather than out of it.
  • Dehydration due to diuresis


We have analyzed mannitol in human plasma. Using our HPLC instruments (Fig. 2), we have determined our LLOQ and ULOQ to be 7.5 and 1500 µg/ml, respectively.

HPLC mannitol analysis

Fig. 2 HPLC

To book our instruments please contact us here.


1. National Library of Medicine. Mannitol. (Internet) (Cited on Aug 2021) Available from:

2. StatPearls. Mannitol. (Internet) (Cited on Aug 2021) Available from:

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HPLC training is for any person (no previous experience needed) who is looking to improve their laboratory skills or learn how to master the HPLC instrument. Depending on your previous experience we will prepare a tailored training to cover everything you may need to know.

Both HPLC training courses are taught on a 1 to 1 basis (maximum 2 people) so that you can take the most out of this training and have plenty of time to adapt to the instrument. We focus on giving you a complete and practical experience, hence by the end of the training, you will feel confident to run by yourself your own set of samples on the instrument.

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Amlodipine in Veterinary Practice

Amlodipine has been used to treat high blood pressure in humans, but it has now been approved for veterinary practice. It is given to cats and dogs to treat hypertension and other associated diseases.

About Amlodipine

This drug is classified as a calcium channel blocker. The heart and arteries contract more forcefully when calcium is present, thus calcium channel blockers relax and widen blood arteries by inhibiting calcium. This effect will lower the blood pressure which prevents heart diseases, heart attacks and strokes.

amlodipine in veterinary practice

Fig.1 Chemical Structure of Amlodipine

Side effects

Like all medicines, amlodipine can have side effects. In animals, common side effects include vomiting, lack of appetite, diarrhea and sleepiness (1). Serious side effects such as severe weakness, changes in urination, abnormal bleeding or rapid heart rate are rare, but can also occur (1).

Hypertension in Cats

Hypertension in cats is a moderately frequent and possibly fatal condition. The most prevalent kind of hypertension in cats is secondary hypertension, which is caused by an underlying systemic condition that impairs the body’s regulatory mechanisms responsible for maintaining normal blood pressure (2). Among these conditions, chronic kidney disease and hyperthyroidism are the most common (2).

Injury to organs can happen due to hypertension. The most prevalent target organ injury found in cats with hypertension is ocular disorders, which can range from retinal detachment resulting in blindness to more subtle indications like hemorrhage or swelling in the back of the eye (2).

Hence, not only can amlodipine treat hypertension, but it can also be given to cats to prevent damage to kidneys, heart, brain, and eyes.

Analysis of Amlodipine in Feline Plasma

Using our HPLC system and LC-MS, we have examined amlodipine in feline plasma. The LLOQ and ULOQ were set for the method as 0.5 ng/ml and 100ng/ml respectively for Amlodipine. The Limit of Detection was calculated as -0.001 ng/ml in feline plasma.


  1. Rania Gollakner. Amlodipine. (Internet) VCA. (cited on 2021 Jul) Available from:
  2. Cornell Feline Health Center. Hypertension: Feline hypertension. (Internet) College of Veterinary Medicine. (updated 2021; cited on 2021 Jul) Available from:

Liquid Chromatography Method Development

Why is Method Development important? 

In the pharmaceutical sector, liquid chromatography procedures are used to assay compounds and quantify impurities present within medicinal products. Method development allows the creation of the best method to test for impurities and compounds which help ensure the quality, safety and efficacy of new products and drugs.

Liquid Chromatography Method Development 

Method development is the process by which the optimal conditions are found for a particular compound to separate it from any contaminants. To design the best method for a particular sample, the following parameters and conditions must be optimized:

  • Selection of chromatographic mode (Reverse Phase, Normal Phase,
    Size exclusion, HILIC, etc.)
  • Selection of stationary phase (C18, C8, Phenyl-hexyl, Biphenyl,etc.)
  • Selection of detector (UV, RID, MS, ELSD)
  • Selection of mobile phase (which buffers; pH of buffers)
  • Flow rate
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  • Injection volume
  • Concentration
  • Calibration Range

HPLC Method Development

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HPLC method development

Fig. 2 Nexera XR HPLC System

Mass Spectrometry Method Development

We have the expertise to design methodologies to quantify most drug-like substances using our Shimadzu LCMS-8040 (Fig.2).

Mass spectrometry method development

Fig.2 Shimadzu LCMS-8040

Our manager Dr. Carolyn Hyde has over 20 years of experience developing methods on HPLC and LC-MS. Click here to contact us for more information on our services. 


Avoomeen. Why Pharma Companies Must Invest in Method Development & Validation (Internet). (Cited on 16th July) Available from: