A lower rate of methaemglobinaemia means the 15 mg dose of primaquine selleck chemical is recommended . For mild–moderate disease, trimethoprim 20 mg/kg/day po in divided doses and dapsone 100 mg od po for 21 days or atovaquone liquid suspension
750 mg bid po for 21 days are alternative options if TMP-SMX is not tolerated or the individual is allergic to TMP-SMX [40,41,53,56]. Glucose 6-phosphate dehydrogenase deficiency (G6PD) levels should be checked prior to TMP-SMX, dapsone or primaquine use (category IV recommendation) G6PD is classified by the level of red blood cell (RBC) enzyme activity and is common in patients of African origin but also some Mediterranean populations, Sephardic Jews and certain Chinese populations. The level of the G6PD enzyme in RBCs is usually higher in patients of African origin than some of the Mediterranean groups who exhibit more severe levels of G6PD enzyme deficiency. Haemolysis may be triggered by oxidant drugs, which include primaquine and dapsone, but can also occur with sulphamethoxazole when used at the higher doses used during iv treatment of PCP [57–59]. G6PD levels should be checked before (or as soon after starting as possible) administering these agents, but treatment should not be delayed
while waiting for the result. As such, it is reasonable to commence first-line treatment with a sulphamethoxazole-containing regimen or if PI3K Inhibitor Library clinical trial the individual is allergic or intolerant an alternative regimen, pending the result of the G6PD assay. If there is evidence of haemolysis this regimen can then be stopped Adenosine triphosphate and an alternative agent, as indicated by disease severity, such as pentamidine or atovaquone (which do not cause oxidant stress in RBCs), may be used if G6PD deficiency
is confirmed. If an individual develops haemolysis, is G6PD-deficient or comes from a population at high risk of significant G6PD deficiency, treatment decisions should be taken in consultation with a haematologist. The overall survival following an episode of PCP approaches 90% . However, a number of individuals will deteriorate and require respiratory support. Early use of continuous positive airway pressure (CPAP) techniques in patients who are hypoxic but not hypercapnic is helpful and may avoid the need for formal mechanical ventilation. It is suggested that early discussion and advice is sought from the ICU for all patients with moderate–severe PCP as many may benefit from close monitoring and advice on initiation of respiratory support. Survival following admission to ICUs experienced in management of severe PCP is now around 40–50%  (see 12 Intensive care). At a minimum, mechanical ventilation should be undertaken in patients who deteriorate early in treatment, or who have good functional status documented prior to the acute respiratory episode (category III recommendation) .