00:00
Let's move on to
the tetracyclines.
00:03
Now tetracyclines are
very commonly used.
00:05
They are broad spectrum
bacteriostatic medications that
are used mostly orally.
00:10
They work both through gram
positive and gram negative
bacteria.
00:15
And they may actually work
with some protozoan as well.
00:19
There's widespread resistance
with two big major mechanisms.
00:24
The first one is through
a development of an efflux pump.
00:27
And that's often seen in
the porteus and the pseudomonas
species.
00:33
And in fact porteus
and pseudomonas are quite
interesting because they
have multidrug pumps.
00:38
So they actually have these
pumps that will eject the whole
host of different medications.
00:42
And the second mechanism of
resistance is through ribosomal
protection proteins that
actually prevent binding.
00:48
Almost like a little
shield around the ribosome.
00:51
The prototypical drug
in the tetracycline family
is actually doxycycline
or tetracycline.
00:59
Doxycycline is used long
term in acne treatment.
01:03
It has a very long
duration of activity.
01:07
And it's relatively non-toxic.
01:09
It's also used in bronchitis,
bronchitis prevention
and leptospirosis.
01:14
Minocycline is used almost
exclusively in acne.
01:18
Demeclocycline is useful in
most infectious diseases.
01:22
And also has a bit of
a diuretic effect.
01:25
So if you go back to hormonal
lectures and the adrenal
lectures that we've spoken
about,
you will see that we have
talked about demeclocycline
and antidiuretic hormones secreting tumors.
01:37
In terms of the toxicity of tetracyclines.
01:40
First of all GI symptoms and
I think all tetracyclines are
suspect with this.
01:46
They have common but minor side effects,
there is very rare episodes of
life-threatening enterocolitis,
but, it's certainly there.
01:54
It does eliminate normal gut flora,
so, you can be prone to bacterial
overgrowth syndrome and candidiasis.
02:03
Now, fetal exposure to this medication,
results in dental enamel dysplasia.
02:08
This is a common exam question,
i do want you to remember this.
02:12
So tetracyclines with fetal exposure,
dental enamel dysplasia.
02:19
In terms of other side effects,
you can get hepatotoxicity,
like most antibiotics, dizziness, vertigo
and that's mostly with doxycycline.