A patient’s weight and medical history can determine the most appropriate colistin dose. The delivery method can also be a factor, as it may be injected intravenously in some cases or inhaled in others; this may change the dosage recommendations. This medication is an antibiotic which may be used to treat a range of infections, and some doctors have their own dosing preferences based on experiences with prior patients. In other cases, they rely on guidelines issued by the facilities they work for.
Due to some regulatory snarls, the concentration of prepared colistin varies by brand. This makes it hard to develop consistent colistin dose guidelines, because each brand is different and conversions between units may be necessary. Broad guidelines on dosing are also not available to provide specific information about how much to prescribe. Manufacturers have some colistin dose recommendations based on their products, as do individual facilities that use the medication.
One issue is weight. Heavier or lighter patients may need a dosage adjustment to ensure they receive a sufficient colistin dose to treat the infection without creating unnecessary risks. Some practitioners may calculate the dose for weight regardless of size. Frequency of dosing is also a consideration, as a patient taking multiple doses each day might need smaller ones to keep serum levels even.
Medical history is also important to consider when formulating a colistin dose. People with renal impairment cannot metabolize the medication as efficiently, which can lead to a buildup in the blood. Consequently, they need a lower dose to reduce the risk of side effects and protect their kidneys. If someone is already taking a medication that interacts with the kidneys, this may be necessary to consider as well, because the combination of the two medications could overload the patient’s metabolism.
Some patients may take inhaled colistin to treat lung infections at the source. A lower dose may be needed in this case because it is delivered directly to the bacteria colonizing the lungs. They inhale a solution with the assistance of a nebulizer that aerosolizes the medication so it can be breathed safely into the lungs. This option may be considered for a patient who already uses a nebulizer to treat asthma, cystic fibrosis, or another pulmonary condition. Rapid medication delivery in these cases can be important because compromises to the patient’s lung function could become fatal more quickly than in healthy individuals.
