what would be the effect of adding fluorine to doxycycline?

Some antibiotics have fluorine. Doxycycline is non-beta lactam and does not have fluorine.

There are only a few antibiotics with fluorine. Below are two:

risperidone and paliperidone comparison

They are both used to treat schizophrenia. The only difference is the alcohol group on paliperidone. I wonder what effect a methyl group in the same place would have. 

what would be the effects of fludrotestosterone or fludroestrogen?

Fludrocortisone and dexamethasone are corticosteroids already in use. 

Below are some un-fluorinated corticosteroids:

clozapine and tetracyclic antidepressants

It is an atypical antipsychotic. 

Tetracyclic antidepressant - Wikipedia

carbamazepine and tricyclic antidepressants

Is there a relationship? Carbamazepine is used to treat epilepsy. 

Carbamazepine - Wikipedia

Tricyclic antidepressant - Wikipedia

aciclovir, ganciclovir, valganciclovir, and valaciclovir comparison

All are antivirals. What would be the effect of replacing an alcohol group with a fluorine or a chlorine atom? 

chlorambucil - a melphalan cousin

It is a chemotherapy drug and has structural similarities with several others. 

Derpetology: melphalan, ifosfamide, bendamustine, and cyclophosphamide comparison

sofosbuvir - another fluorouracil cousin

It is used to treat hepatitis C.

Derpetology: fluorouracil and its cousins (fluoropyrimidine)

cephalosporins, beta lactams, and fluorouracil

Below are the general structural formulas for cephalosporin and beta lactam antibiotics. What would be the effect of substituting the sulfur ring with fluorouracil?

norepinephrine, methyldopa, dopamine, and epinephrine comparison

Norepinephrine increases blood pressure and methyldopa reduces it. But why? Could new blood pressure medicines be made by substituting a carboxylic acid group for an amino group? 

zidovudine - another fluorouracil cousin

It is used to prevent and treat HIV/AIDS. I wonder about the effect of adding a fluorine to it. 

Derpetology: fluorouracil and its cousins (fluoropyrimidine)

seratonin and auxin comparison

Seratonin regulates mood, appetite, and sleep. Auxin coordinates plant growth and behavior.

coping with mortality

Religion, with its various teachings about an afterlife, is the traditional way people have coped with knowledge that they will die. The other popular method is parenthood. In this way, people know part of them will live on in their offspring. However, there have always been those for whom religion and children have not been enough to soothe death anxiety. They try to make an immortal legacy through conquests, monuments, inventions, discoveries, great works of art, or other achievements. The growth of scientific knowledge has eroded religious belief, and so denial has become the most popular method of dealing with death anxiety, at least in the industrialized world (the panic over COVID-19 made that clear).  

In my view, all these methods are wrong. The first step is to acknowledge that not only do we die, but we will almost certainly be forgotten not long after. There are only a few hundred people still remembered millennia after their deaths. Even if we have children, whatever was unique about our DNA will be diluted to insignificance after a few generations. There are people who try to attach their identity to a nation or even the human race as a whole, but even that is flawed. Nations come and go. Few last more than a few centuries. If humanity follows the same path as 99% of other species, it will go extinct within a few million years.

I find solace in looking at the natural world. Through evolution, every living thing is related to me in some way, and this has been proven through DNA analysis. Life on earth has survived for billions of years through many cataclysms, and it will almost certainly continue into the far future regardless of what humans do. Everyone could benefit from looking at the big picture as shown in natural history museums. Enjoy the moment. Don't cry because it's over, smile because it happened. Life finds a way.

Enter Life - Faith Hubley, 1981

Helion Prime - Life Finds A Way (Official Video)

Carl Sagan - 'A Glorious Dawn' ft Stephen Hawking (Symphony of Science)

cytarabine - another fluorouracil cousin

It is a chemotherapy drug.

Derpetology: tegafur and gemcitabine comparison - fluorouracil cousins

on jumping through hoops

Bertrand Russell said that after survival needs are met, people desire only four things: stuff, attention, status, and power. Stuff is money and what it can buy. The need for attention is what drives the behavior of actors, rock stars, etc. Status is what you get by proving you are better than someone else. Power is the ability to make people do things they don't want to do. 

Everyone is in a social hierarchy. Your position in it is based on your status. Generally, you gain status by jumping through hoops, that is, completing tasks, often ones that are needlessly difficult. For example, the members of the military with the highest status (generals, fighter pilots, Navy SEALs, etc.) are the ones who completed the longest and most difficult courses. Because the tasks are hard, few complete them, and as such the ones who do have higher status because there are fewer of them. 

In a similar way, doctors and lawyers have more status than cooks or drivers because the former must go through much more training and there far fewer of them. 

So why do people desire status? I think it is mainly because it is a good way to fulfill the other three desires. Billionaires and celebrities have an easy time getting stuff, attention, and power. Prisoners and homeless people do not. An old saying goes that money and power always find each other. Another one guys that men lose money if they chase women, but they never lose women if they chase money. 

It all boils down to knowledge. Seek that instead of jumping through hoops. 

4-aminosalicylic acid, isoniazid, and ethionamide comparison

All are used to treat tuberculosis. All have a keto (thioketone in one case) group, an amino group, and a 6-sided ring. I suspect there are other potential tuberculosis drugs that have the same functional groups. 

chronology of common anesthetics

Once the first two were discovered and analyzed, there was a gradual push to combine them and make different asymmetrical halogenated ethers. The last one is a somewhat asymmetrical ester salt. I suspect another anesthetic could be made by chlorinating and/or fluorinating diethyl ether.  

19th century 

20th century