Phosphate esters of clindamycin and of 3-hydroxymethylphenytoin (as sodium salts) are freely soluble in water and allow painless injections. The free concentrations of iron or of calcium are reduced by using calcium gluconate or laevulinate for intravenous injections and iron–sorbitol citrate for intramuscular injections. 47Įxcessive concentrations of the active compound at the injection site (initial peak concentrations) are avoided by masking the irritating agent through complexation. Other factors include precipitation of the drug at the injection site, and localized cell lysis. 47 Among the factors responsible for painful injections, the most important are the drug's solubility in aqueous medium, the viscosity, the pH and the hypo- or hyperosmotic character of the injected drug solution, the amount of the injected volume, the site of injection, the pain tolerance of the patient, and the technique of administration. Injection pains are usually accompanied by haemorrhage, oedema, inflammation and tissue necrosis. When an initially painful intravenous or intramuscular injection must be administered repetitively, patient reluctance develops. Wermuth, in The Practice of Medicinal Chemistry (Second Edition), 2003 B Avoidance of painful injections Parecoxib: In a double-blind, randomized, placebo-controlled study with venous occlusion in 150 patients, the incidence of any pain was significantly less with parecoxib 40 mg (26%) than with parecoxib 20 mg (44%) and saline (58%). However, in another study in 101 patients, ketorolac 10 mg given before propofol had no effect. In a double-blind, randomized, placebo-controlled study in 90 patients pre-treatment with ketorolac + lidocaine was more effective than no pretreatment.

A lower dose of ketorolac 10 mg with venous occlusion for 120 seconds achieved the same effect. Ketorolac: In a double-blind, randomized study in 180 patients pretreatment with intravenous ketorolac 15 mg and 30 mg reduced propofol-induced pain. In Meyler's Side Effects of Drugs (Sixteenth Edition), 2016 Non-steroidal anti-inflammatory drugs (NSAIDs)įlurbiprofen: In 250 patients intravenous flurbiprofen 50 mg immediately before propofol injection completely abolished injection pain and was more effective than lidocaine when flurbiprofen was given 1 minute before propofol injection it was less effective.

Painful shots