Injections endotoxin limit

The absorption of drugs in solution from intramuscular and subcutaneous sites of injection is limited by the perfusion rate. Failure to recognize this important concept has resulted in patient death. For example, morphine sulfate is often administered subcutaneously in a dose of 10 mg per 70 kg of body weight. This dose is sufficient to produce analgesia in 70% of patients with moderate to severe pain. However, in the setting of circulatory collapse and shock (e.g., septic shock in bacteremia due to release of endotoxin) in which the peripheral circulation may be impaired, morphine is not absorbed. Cases have been reported in which the lack of analgesia prompted the additional injection of morphine, all of which remained at the injection site and in the subcutaneous capillary bed. When the peripheral circulation improved, the massive amount of morphine that had collected became absorbed and death ensued, which was primarily due to respiratory depression. 

Pyrogenic contamination is detected using two tests. In the older method, rabbits are injected with product samples, and rectal temperature is measured. Compendial limits are established with respect to how much temperature increase is permitted before the product is judged to be free or contaminated with pyrogens. The newer method involves a relatively simple in vitro technique called the Limulus Amebocyte Lysate (LAL) test. It is based on the high senstivity of amebocytes of the horseshoe crab (Limulus) to the lipopolysaccharide component of endotoxins originating from Gramnegative bacteria. The LAL test is now the USP method of choice with endotoxin limits established for most SVIs. ... 

Municipal water systems usually contain 5-50 EU/ml of endotoxin. Pharmaceutical waters are treated by ultrafiltration, distillation, or reverse osmosis to separate endotoxin from water.f The principal source of endotoxin is bacteria within a water system in the form of biofilm or colonies entrapped in resin beds, etc. A water system will be contaminated unless there is an ongoing sanitization program. The endotoxin limit for Water for Injection was set at 0.25 EU/ml because it is a critical vehicle and a major source of pyrogens. 

Another important consideration for excipients to be used in parenteral products is their quality, particularly in microbiological terms. Commonly used parenteral excipients can often be obtained in an injectable grade which will meet strict bioburden and endotoxin limits. Pharmacopoeial grades of other excipients may be acceptable, but it is prudent to apply in-house microbiological specification limits, where none are present in the pharmacopoeias. For non-pharmacopoeial excipients, the best approach is always to purchase the highest grade available and apply internal microbiological specification limits. 

Excipients used in injectable formulations have to meet several stringent requirements. A positive identification test uniquely applicable to the excipients is required (e.g., infrared spectrophotometry and chromatography). It is important that manufacturers identify and set appropriate limits for impurities. These limits should be based upon appropriate toxicological data, or the limits described in national compendial requirements. Manufacturing processes should be adequately controlled so that the impurities do not exceed such established specifications. Solvents or catalysts used in the excipient production process should be removed to appropriate levels. If naturally derived, excipients should meet endotoxin levels and may require further testing for bovine spongiform encephalopathy (BSE) /... 

Water used in manufacture of sterile parenteral products must comply with pharmacopeial limits for endotoxin of no more than 0.25EU/ml (limits in the USP and PhEur for water for injection). In principle water complying with this limit can be produced by... 

The Ph. Eur. gives limits for radiopharmaceuticals in general but for some individual radiopharmaceutical preparations as well. In most radiopharmacy departments the endotoxin content of radiopharmaceutical preparations is not tested before injection. In some situations, e.g. development of a new preparation process or when using generators for longer periods of time (weeks to some months) endotoxin testing may be useful (see further Sect. 19.3.4). 

For approximately 80 raw materials the Ph. Eur. has set limits for endotoxin levels if they are intended for parenteral dosage forms. These include among others dextran, sorbitol and mannitol, sodium chloride, trometamol, water for injections. 

An example of calculating the limits for endotoxins A morphine containing injection solution with the strength of 100 mg/5 mL has been prepared. Because the product will be administered parenterally a bacterial endotoxins test has to be performed. Therefore the administration route has to be known is this intravenous or intrathecal or epidural. For endotoxins in intravenous administration the requirement is maximally 5 EU/kg body weight during 1 h. Based on a body weight of 70 kg this means 350 EU/h. Secondly the maximal dose (in volume of the product per hour) will determine the actual limit. This depends on the need of the patient as well. If he needs the full 5 mL, this makes the requirement for the product to be 350 EU/5 mL = 70 EU/mL. 

In humans, contact with LPS may occur not only during a bacterial infection but also via LPS-contaminated medicaments and solutions administrated intravenously (parenteralia). Since the biological effects of LPS may appear even at concentrations of 1 ng per 1 kg of body weight, drugs intended for parenteral use, have to be endotoxin-free , i.e., thoroughly depyrogenated. In fact parenteralia have to comply with LPS threshold limits (in EU , endotoxin unit) regulated by pharmacopoeias. For example, tetracycline hydrochloride may not contain more than 0.5 ELf/mg. Similar limits exist for insulin (0.8 EU/insulin unit), hyaluronidase (2.3 EU/ hyaluronidase unit), the sodium salt ofheparin for injection (0.003 EU/heparin unit). ... 

Tests for microbial limits may also have to be considered depending on the nature of the API, its method of manufacture, and its intended use. Sterility testing may be appropriate for APIs that will be used in parenteral or oral solution products that are sterile. Endotoxin testing may be needed for APIs intended for injectable products. Testing for the total count of aerobic microorganisms, yeasts, and molds and the absence of specific objectionable bacteria, such as Staphylococ-cus aureus, Escherichia coli. Salmonella, and Pseudomonas aeruginosa, may also be required. The tests described in the various compendia are generally used. 

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