🔴 Mechanism of Action 🔴

🔺 Drugs for erectile dysfunction :-

🔺How normal erection of penis takes place??? .... When sexual arousal then increases blood flow to the penis and relaxes the cavernosal sinusoids so that they fill up with blood, making the penis rigid, elongated and erect. Nitric oxide (NO) released from parasympathetic nonadrenergic noncholinergic (NANC) nerves and vascular endothelium is the major transmitter causing relaxation of smooth muscle in corpus cavernosum and the blood vessels supplying it; Ach and PGs also play a role.

1. Androgens :-

Hypogonadism is an infrequent cause if ED (erectile dysfunction) . Parenteral testosterone esters or transdermal testosterone therapy is effective only when androgen deficiency is proven to be responsible for loss of libido and erectile dysfunction.

2. Phosphodiesterase-5 (PDE-5) inhibitors :-

NO (Nitric Oxide) causes smooth muscle relaxation by generating cGMP intracellularly..... Promote dephosohorylation of myocin light chain kinase ( MLCK) .... so that myocin interact with actin. Inhibition of PDE-5 is degrading isoenzyme is cavernisal and vascular smooth muscle, results accumulation if cGMP and marked potentiation of NO action.

e.g. Sildenfil, Vardenafil & Tadalafil . Are selective PDE-5 inhibitors found effective in majority of patients.

3. Papaverine /phentolamine induced penile erection (PIPE) therapy.:- (Use these only in cases not responding to sildenfil and alprostadil.

4.Prostaglandin E1 :-
( Use by directly injectin into Corpus cavernosum)

🔴ADRS OF PDE5 INHIBITORS 🔴
✔️Headache
✔️Nasal congestion
✔️Dizziness
✔️Facial flushing
✔️Fall bp
✔️Impairment of colour vision specially blue n green discrimination
✔️Gastric reflux and dyspepsia
✔️

🔴 Mechanism of Action 🔴

🔺Estrogen (female sex hormone) :-

Estrogen acts on nuclear receptors lacated within target cells ( details in general pharmacology).

Estrogen receptors (ERs) designated ER alpha & ER beta.

🔸ER apla :- Dominates in uterus, vagina, breast, bone, hypothalamus and blood vessels.

🔸ER beta :- Predominates prostate gland of Males and ovaries of Females.

Estradiol binds to both the receptors with equal affinity but certain ligands have different affinities.

🔺 Actions :-

🔸1. Sex organs :- Estrogen bring about pubertal changes in female including growth of uterus, fallopian tubes and vagina etc.

🔸2. Secondary sex characters.

🔸3.Metabolic effect :- estrogens are weaker anabolic than testosterone.

🔺 Classification of Estrogens.

🔸A. Natural estrogens:-
Estradiol
Estrone
Estriol

🔸B. Synthetic estrogens
I. Steroidal e.g. Ethinylestradiol
Mestranol
Tibolone.
II. Nonsteroidal
e.g. Diethylstilbestrol
Dienestrol
Hexestrol.

🔴ADRS OF ESTROGEN🔴
✔️Gynacosmastia and feminization in males
✔️Fusion of epiphyseal and reduction of adult stature when given to children
✔️Risk of irregular bleeding
✔️Endometral carcinoma
✔️Breast cancer
✔️Gallstones
✔️Benign hepatomas
✔️Migraine
✔️Endometriosis