A drug for blocking various infections. Blocks malaria, sleeping sickness, and plague. Take every five days.
Penoxycyline is a medical drug in RimWorld which was introduced in Alpha 16, and succeeds Malari-Block. Unlike its predecessor, Penoxycyline blocks against 3 diseases: malaria, sleeping sickness, and the dreaded plague - whereas Malari-block only blocked against malaria.
Like Malari-Block; Penoxycyline can either be purchased from traders, or crafted at a drug lab - but for a mere 3 neutroamine as opposed to the 5 which Malari-block took. However, in order to make Penoxycyline, you need to have penoxycyline production researched, which in turn requires drug production, and Neutroamine has to either be purchased from traders, or found in cargo pods.
Contrary to its description, Penoxycyline cannot fully prevent disease. Instead, it provides immunity against them.
Administering Penoxycyline instantly boosts the immunity of the diseases it protects against to 61% if it's lower than that.
As diseases cannot be acquired at 60%+ immunity, and Penoxy sets it to 61%, this means that Penoxycycline offers true immunity to plague & sleeping sickness for 12 hours, and malaria for 8 hours. After that period, it reduces the probably of that particular pawn getting sick. There is a brief time before it decays below the threshold.
The weird part is that the game first picks how many pawns will get sick, regardless of immunity, and then next picks which pawns get sick, weighted by immunity. If only one of your pawns has taken penoxy, and took it 24 hours ago, that pawn is 1/50th as likely to get sick as the other pawns. But if all of your pawns have taken it 24 hours ago, they're all just as likely to get sick and the same number of pawns total will get sick. But they'll still be starting at 59% immunity, pretty much guaranteeing survival, and a very short period of actual sickness. (A young, healthy pawn will be at 90%+ immunity when the plague/sleeping sickness is revealed; malaria never revealed at all).
For plague & sleeping sickness, Penoxycycline prophylaxis may be useful for all healthy pawns; it can be taken reactively and still add 30%+ immunity, eliminating the need for bed rest or treatment to survive (and if treatment is provided it won't reach serious stages).
Malaria does need proactive Penoxycycline. A healthy pawn will develop 55% immunity in the 4.6 days it takes to reveal itself, so reactive penoxy only adds 5%, though more will be added if the pawn has a weakened immune system.
Penoxy taken every 5 days will maintain a minimum of 46% immunity to malaria, so healthy pawns will never have a visible Malaria infection. But taken every 9 days, a healthy pawn will still develop immunity before malaria hits Major severity without any treatment or bed rest. A solo jungle explorer looking to conserve their supply might stretch it out to every 12 days (which will avoid extreme without any treatment or bed rest), or if they're particularly brave/desperate, every 15 days (but then there is a small risk that bed rest will be necessary). Taken every 20 days, Penoxy offers no guaranteed immunity, but on average will cut off 2.5 days before immunity is acquired.