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 Case two-continued>>>

استعرض الموضوع السابق استعرض الموضوع التالي اذهب الى الأسفل 
كاتب الموضوعرسالة
Mohammad
مشرف قسم خمسه فرفشه
مشرف قسم خمسه فرفشه


ذكر

عدد الرسائل : 313

العمر : 30
العنوان : ]
العمل : ]
تاريخ التسجيل : 23/08/2008

مُساهمةموضوع: Case two-continued>>>   الإثنين يناير 12, 2009 6:24 pm

Our patient decided to consult his family physician, who told him that his
problem(Erectile Dysfunction) may be related to his current medication
(Tenormin).

The family physician prescribed him Norvasc,and scheduled follow-up
visits.

Unfortunately,our patient's condition didn't improve.


The family physician prescribed Viagra,50mg, to be used 1 hour prior to
sexual intercourse.

The patient read the included pamphlet, and in the "side effects" section he
found that the drug may lead to hypotension and hearing loss.

The patient called his doctor immediately,he wondered if there is a possible
additive hypotensive effect of the two medications....

Questions:

Can you answer the patient's question?

Hint:
Norvasc is popular trade name for Amlodipine
Sildenafil is the active ingredient in Viagra.
الرجوع الى أعلى الصفحة اذهب الى الأسفل
Mohammad
مشرف قسم خمسه فرفشه
مشرف قسم خمسه فرفشه


ذكر

عدد الرسائل : 313

العمر : 30
العنوان : ]
العمل : ]
تاريخ التسجيل : 23/08/2008

مُساهمةموضوع: رد: Case two-continued>>>   الإثنين يناير 12, 2009 7:47 pm

Viagra

It is an extremely popular drug! It is known by lay people as "the blue pill"
and "Vitamin V" (الحبة الزرقاء)

It was developed and is being marketed by the pharmaceutical company Pfizer.

It is available in the Egyptian market as tablets 100,50 and 25 mg







Pfizer:

Pfizer is a major pharmaceutical company, which ranks number one in the world
in sales.The company is based in New York City.

Logo of the company:



Mechanism of action:

A. Physiology of Erection
Penile erection is accomplished by engorgement of cavernous spaces within the
corpora cavernosa under near-arterial pressures and involves:

1-dilation of arterial inflow
2-relaxation of corpora cavernosa smooth muscle
3-constriction of venous outflow.

The 1st and 2nd event occur as the following:

The relaxation of the penile arterial smooth muscle, the corporal smooth muscle,
and therefore erection is under the control ofthe autonomic nervous system.

The principal neural mediator of penile smooth muscle relaxation is nitric oxide (NO).

Note:
Three isoforms of NO synthase (NOS) that convert L-arginine to NO have been
identified: neuronal (nNOS; type I NOS), inducible(iNOS; type II NOS), and
endothelial (eNOS; type III NOS). Which one do you think is present in the
penile nerve endings?

Terminals containing nNOS densely innervate the corpus cavernosum and its arterial
supply.NO derived from the endothelium lining penile arteries and cavernosal
sinuses also participates in the erectile response.

Now, how does NO work?

-The arterial dilator actions of NO and its relaxant effect on the smooth muscle of
the corpus cavernosum are mediated by the activation of soluble guanylate
cyclase and production of cGMP, which acts as a second messenger.

-Accumulation of cGMP leads to smooth muscle relaxation.

-The degradation of cGMP into its inactive form, GMP, is catalyzed by
phosphodiesterase enzymes.
The predominant isoform of this enzyme in the corpus cavernosum is PDE5.

Inhibitors of the activity of this enzyme prevent the breakdown of cGMP,resulting in enhanced penile erection.

B.Mechanism of action of Sildenafil.

Sildenafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP
in the corpus cavernosum.

The molecular structure of sildenafil is similar to that of cGMP and acts as a
competitive binding agent of PDE5 in the corpus cavernosum, resulting in more
cGMP and better erections.

Indications:
1-Erectile Dysfunction.

2-Pulmonary Hypertension: (this fact was mentioned by the pediatric
cardiologist,Dr Ayman Sabry during one of clinical sessions)

Because PDE-5 is primarily distributed within the arterial wall smooth muscle
of the lungs and penis, PDE-5 inhibitors can be used in pulmonary hypertension.

It relaxes the arterial wall, leading to decreased pulmonary arterial resistance and pressure. This in turn reduces the workload of the right
ventricle improves symptoms of right-sided heart failure.

Side effects:
The side effect profile can be easily expected.
Most of them are related to vasodilator effect of the drug!!

1-Headache.
2-Flushing.
3-Nasal congestion.
4-Hypotension.
5-Priapism: is a potentially harmful and painful medical condition in which the
erect penis does not return to its flaccid state, despite the absence of both
physical and psychological stimulation, within four hours. Priapism is considered a medical emergency.

-Other side effects:
-Blurred vision,photophobia.
-Hearing loss.

Contraindications:
-In patients receiving organic nitrates (such as nitroglycerin).Use of
sildenafil at the same time can lead to profound hypotension.

-Impairment of hepatic or renal function.
-Hypotensive patients.

Dose:
The dose of sildenafil for erectile dysfunction is 25 mg to 100 mg taken not
more than once per day between 30 minutes and 4 hours prior to sexual intercourse.

Task:

Please search for the reason of this grave interaction between Organic
nitrates and sildenafil.
الرجوع الى أعلى الصفحة اذهب الى الأسفل
Mohammad
مشرف قسم خمسه فرفشه
مشرف قسم خمسه فرفشه


ذكر

عدد الرسائل : 313

العمر : 30
العنوان : ]
العمل : ]
تاريخ التسجيل : 23/08/2008

مُساهمةموضوع: رد: Case two-continued>>>   الإثنين يناير 12, 2009 8:22 pm

Norvasc

Available as tablets 5,10 mg

Another product of pfizer.

Active ingredient: Amlodipine , a calcium channel blocker.

Dose:
Five or ten mg once daily (initial treatment can start as low as 2.5 mg per day).

الرجوع الى أعلى الصفحة اذهب الى الأسفل
amani_muhammad
مشرفه قسم الشعر
مشرفه  قسم الشعر
avatar

انثى

عدد الرسائل : 225

العمر : 31
العنوان : ismailia
العمل : medical student
الهوايه : القراءة، الكتابة الأدبية ، الخط العربي،التصوير الفوتوجرافي، السفر
تاريخ التسجيل : 19/07/2008

مُساهمةموضوع: رد: Case two-continued>>>   الإثنين يناير 12, 2009 10:58 pm

thank u again and again

and again i am not sure of my answer as i only read the book and apply what i understand. these cases need a clinical experience that i have a little of
anyway, i have found that the effect of sildenafil does not appear in the absence of sexual stimulation, so it cannot be used as " additive therapy" to lower blood pressure
i think it will lower blood pressure but not to a dangerous level.headach, flushing, and nasal congestion may be found due to vasodilation. i have found that it is absolutely contraindicated to coadminstration with nitrates as viagra potentiates the effect of nitric oxide and may lead to severe hypotension
الرجوع الى أعلى الصفحة اذهب الى الأسفل
Mohammad
مشرف قسم خمسه فرفشه
مشرف قسم خمسه فرفشه


ذكر

عدد الرسائل : 313

العمر : 30
العنوان : ]
العمل : ]
تاريخ التسجيل : 23/08/2008

مُساهمةموضوع: رد: Case two-continued>>>   الثلاثاء يناير 13, 2009 12:31 am

Thank you dr Amani for your rapid and very good response.

I hope this discussion would help us improve our clinical experience very much,
and please make sure that I do my best to verify the information I post.

The patient's worry here is not about the use of sildenafil as hypotensive agent;
instead he is worry about having hypotensive attacks due to the coadministration
of two drugs that have hypotensive effects.

His question is very logic, and on the net, I found many articles that deal with this problem.

Now relax, and read this one:
http://www.medicinenet.com/script/main/art.asp?articlekey=17038

As you noted, no significant added risk exist if sildenafil is added to antihypertensive medications. Hypotension occur with the same frequency
in patients whether or not they receive the antihypertensive medication.


Regarding the concomitant use of nitrates;

Did you read the mechanism of action of Sildenafil??

If so, now let us review the mechanism of action of organic nitrates...

Organic nitrates is converted within the vascular smooth muscle cells first into
nitrites, then NO is formed.

NO works by increasing the activity of Guanylate cyclase,thereby increasing the
level of cGMP,hence causing smooth muscle relaxation.

Within the vascular smooth muscle cells,cGMP is degraged by phosphodiesterase
enzyme(I am not sure about its number but I think it is PDE3)

Although Sildenafil is spcific for PDE5, this specificity isn't 100%, so it may partially
inhibits other isoforms of PDE including PDE3,leading to increased levels of NO and
prolonged relaxation, culminating in dangerous and potentially fatal hypotension.

Effect of Sildenafil on visual function:
These visual effects appearto be related to the weaker inhibiting action of
sildenafilon PDE6, which regulates signal transduction pathways in theretinal
photoreceptors.



We,as physicians, are prone to such questions,and me,myself, was asked about the effect of Sildenafil on diabetes, and I didn't know the answer!!
Can you find the answer??


Please, send me your opinion in the cases and the answers.

Do you think there is overinclusion of details??

In the next cases,we will focus on pediatrics in sha'a Allah.
الرجوع الى أعلى الصفحة اذهب الى الأسفل
amani_muhammad
مشرفه قسم الشعر
مشرفه  قسم الشعر
avatar

انثى

عدد الرسائل : 225

العمر : 31
العنوان : ismailia
العمل : medical student
الهوايه : القراءة، الكتابة الأدبية ، الخط العربي،التصوير الفوتوجرافي، السفر
تاريخ التسجيل : 19/07/2008

مُساهمةموضوع: رد: Case two-continued>>>   الثلاثاء يناير 13, 2009 4:16 pm

first, i intend to stop " thanks" beacuse this idea is realy realy great and a million " thanks" will not be enough . only (gazakallho 7'ayran)may suffice
the cases are exxcelent. i have told my colleages today about them and invited them to share. please go ahead and in sha'allah many will share the discussion. the information you wrote may be too much - honestly- but i believe that interests of 2 persons are absolutely different. for me i may prefere the clinical data and don't like the pharmacological information very much, this does not mean that every doctor does the same thing.
shortly, go on and write down what u want. information that does not benifit absolutely does not harm
i'm impressed by your answers and i believe you will be a famous successful doctor soon in sha'allah
best wishes
i'm waiting for the next case
الرجوع الى أعلى الصفحة اذهب الى الأسفل
amani_muhammad
مشرفه قسم الشعر
مشرفه  قسم الشعر
avatar

انثى

عدد الرسائل : 225

العمر : 31
العنوان : ismailia
العمل : medical student
الهوايه : القراءة، الكتابة الأدبية ، الخط العربي،التصوير الفوتوجرافي، السفر
تاريخ التسجيل : 19/07/2008

مُساهمةموضوع: رد: Case two-continued>>>   الثلاثاء يناير 13, 2009 4:25 pm

for your question, i have found two studies , one of them in 1999 and the other in 2002, both confirmed that sildenafil is an effective, safe and well tolerated in patients with diabetes mellitus
الرجوع الى أعلى الصفحة اذهب الى الأسفل
Mohammad
مشرف قسم خمسه فرفشه
مشرف قسم خمسه فرفشه


ذكر

عدد الرسائل : 313

العمر : 30
العنوان : ]
العمل : ]
تاريخ التسجيل : 23/08/2008

مُساهمةموضوع: رد: Case two-continued>>>   الثلاثاء يناير 13, 2009 9:12 pm

شكرا يا دكتورة أماني على كلماتك المشجعة حقا ، وهذه الكلمات ستدفعني إلى الأمام.

الإيجابية شيء مهم في كل حياتنا، بما فيها دراسة الطب، وأنت-ما شاء الله-لك قدر كبير منها. فأسأل الله لكي الزيادة.


وبالنسبة للمعلومات الإكلينيكية ، فأنا -في وجهة نظري-لا بد أن يدعمها علم نظري، وأن لا تؤخذ كما هي، بل أن نربطها في أذهاننا بالأساس العلمي الذي قامت عليه.

وهذا له فائدتان:

1-أن يصبح العلم ممتعا

2-تثبيت المعلومة


وإن شاء الله سأبعث الحالة الجديدة عما قريب جدا.

جزاكم الله خيرا.
الرجوع الى أعلى الصفحة اذهب الى الأسفل
snow white
عضو شرف
عضو شرف


انثى

عدد الرسائل : 13

العمر : 30
العنوان : الإسماعيلية حي السلام
العمل : طالبة
تاريخ التسجيل : 20/11/2008

مُساهمةموضوع: رد: Case two-continued>>>   الثلاثاء يناير 13, 2009 10:40 pm

السلام عليكم
جزاك الله خيراً يا دكتور محمد على الفكرة الأكثر من رائعة وإن شاء الله هنشارك لأنها مفيدة من غير شك
وفعلا ربنا يجعلها في ميزان حسناتك
مستنية الحالة الجديدة عشان أشارك إن شاء الله
الرجوع الى أعلى الصفحة اذهب الى الأسفل
Mohammad
مشرف قسم خمسه فرفشه
مشرف قسم خمسه فرفشه


ذكر

عدد الرسائل : 313

العمر : 30
العنوان : ]
العمل : ]
تاريخ التسجيل : 23/08/2008

مُساهمةموضوع: رد: Case two-continued>>>   الثلاثاء يناير 13, 2009 11:28 pm

أهلا وسهلا بكي يا snow white,


مشاركتك تسرنا ، وربنا يرزقنا الإخلاص.


الحالة الجديدة بكرة إن شاء الله لأن النت بطيء النهاردة ، وربنا يستر وما يقطعش

أنصحك بقراءة الحالات السابقة لأنها مفيدة بإذن الله
الرجوع الى أعلى الصفحة اذهب الى الأسفل
 
Case two-continued>>>
استعرض الموضوع السابق استعرض الموضوع التالي الرجوع الى أعلى الصفحة 
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