MCQ: Carbamazepine

Q1) Which of the following statements is true about carbamazepine:-

A) It is indicated in complex partial seizures.

B) It is an enzyme inhibitors

C) It can cause megaloblastic anaemia

D) It is the drug of choice for status epilepticus.

#recentNEET

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#pharmacology 

So, the answer to the above question is an option 

A) It is indicated in complex partial seizures.

Let's get started with Carbamazepine:-

It is an antiepileptic drug that acts by lengthening the inactivated state of the Na+ channel. 

Uses:-

1) DOC for Partial seizure/trigeminal neuralgia.

2) Bipolar disorder.

3) Acute mania

4) GTCS.

Let's rule out other options:-

Option B) It's an enzyme inducer. It is a substrate as well as inducer for CYP3A4 and CYP2C9. Oxcarbazepine is a less powerful CYP enzyme inducer.

Option C) Carbamazepine causes agranulocytosis or aplastic anaemia and not megaloblastic anaemia.

Other side effects include:

1) Hyponatremia: Delayed and more common in the elderly. Risk is higher in Oxcarbazepine.

2) Hypersensitivity

4) Hepatoxicity 

3) Steven Johnson syndrome (Associated with HLA-B 1502 gene)

4) Ataxia 

4) Blurred vision/ Diplopia 

For the last two side effects, we need TDM for adjusting the dose. Remember, Ataxia and Blurred vision is not a Idiosyncratic reactions.

Let's do questions related to Carbamazepine!

Q1) What adverse effect is risked to ongoing valproate therapy?

-Hepatotoxicity.

Q2) A cancer patient is on anticancer drugs (vincristine etc) and develops multiple episodes of seizures, refractory to diazepam and lidocaine. Blood tests show elevated ADH and euvolemic hyponatremia. Which drug can be used to treat this patient?

- You can't use Carbamazepine because it causes increase sensitivity of renal tubules to ADH levels. 

In this case, we use Phenytoin which causes a decrease in ADH secretion and corrects hyponatremia.

~Ojas

Acute rheumatic fever and RHD - diagnostic criteria

Hello

Diagnosis of ARF and RHD based on modified Jones' criteria - let's review:

Introducing Cardiowesome

Hi everyone, 

As you already know I have started my Cardiology Fellowship this year. I'm going to post a lot of blogs on cardiovascular diseases that might of not be palatable for medical students. Only some of these posts maybe helpful (pharmacology related, EKG ones, and basic pathophysiology of cardiovascular diseases). 

I understand that the majority of my posts will be limited to a specialized group of cardiologists, echocardiographers, emergency medicine physicians, critical care professionals, POCUS users, electrophysiologists, heart failure specialists, and interventional cardiologists.

This is why, I'm introducing a new label on the medicowesome blog called cardiowesome. These are advanced posts targeted for cardiology fellows and trainees.

I hope you enjoy reading them and learning with me. 

-IkaN (Nakeya Dewaswala Bhopalwala) 

S' Tissue Doppler Imaging - Derived Tricuspid Lateral Annular Systolic Velocity mnemonic

S’ Wave: Tissue doppler imaging-Derived Tricuspid Lateral Annular Systolic Velocity

S’ value less than 9.5 cm/sec indicating RV dysfunction. Mnemonic... If you stare at the number long enough you'll see 9.5 in it lol. 

The first peak above baseline that is timed with the QRS represents isovolumetric contraction and not the tricuspid annular velocity.

-IkaN (Nakeya Dewaswala Bhopalwala) 

Relative wall thickness 0.42 mnemonic

The RWT reports the relationship between the wall thickness and cavity size. It is an index of LV concentricity. 

The golden number to remember for RWT is 0.42 as it allows further classification of LV mass increase as either concentric hypertrophy (RWT >0.42) or eccentric hypertrophy (RWT ≤0.42). 

Since there are so many numbers to remember in echocardiography, I made a mnemonic for RWT. 

Relative = 0 (Relative zero)

Wall = 4 (4 letters in the word wall)

Thickness = 2 (2 strokes in the letter T) 

Hope this helps! 

-IkaN (Nakeya Dewaswala Bhopalwala) 

Rheumatic chorea - variable clinical presentation timelines

 Hello

Variations in clinical presentation of rheumatic/ sydenham's chorea -

Relative wall thickness on echocardiography

Relative wall thickness (RWT) is calculated as two times posterior wall thickness (PWT) divided by the left ventricular internal diastolic diameter (LVIDd). 

RWT allows further classification of LV mass increase as either concentric hypertrophy (RWT >0.42) or eccentric hypertrophy (RWT ≤0.42).

-IkaN (Nakeya Dewaswala Bhopalwala) 

Infective endocarditis vegetations - which side do they develop?

Infective endocarditis vegetations tend to develop on the upstream side of the valve (flow side) which is typically tend to be the lower pressure side. These are the ventricular side of the aortic valve and the atrial side of the mitral or tricuspid valve. 

Image shows parasternal long axis view on echocardiography showing vegetations on the mitral and aortic valve (green vegetations because vegetables are green lol!)

-IkaN 

COVID - OMICRON

Hello friends!

This post is about omicron variant of COVID.

Why do we have to know about any new variants?

✓ more infectious than previous one?

✓ if it's more virulent?

✓ any diagnostic difficulties?

✓ treatment failure?

✓ does previous vaccine work for it?

Basically this OMICRON has more than 30 different mutations on surface of S1 or S2 spike protein with lineage number B.1.1.529 variant of concern (voc).

Preliminary data shows that it is highly infectious but the data is limited. We need to wait for further studies.

Most of the vaccines are targeting 'S' spike protein so antibodies are produced against 'S' spike. Risk of vaccine failure due to 'S' spike mutation is still a point of concern but data is limited now.

Diagnostics- most of the other targets (including N and RdRp genes) remain unaffected. These RTPCR tests detect atleast 2 different SARS-CoV-2 targets, which serves as a backup in case mutation arises. Current PCR tests can detect this variant. 'S' gene target failure can occur if not detected.

Severity of disease - more in immunocompromised and extremes of age groups.

Effectiveness of vaccines - Antibodies decrease severity and death .

Reinfection is higher with omicron.

Treatment - steroids and IL-6 receptor blockers are still effective.

So, be cautious but don't panic! 

That's all!

Dr.Madhuri 

EVALUATION OF THYROID FUNCTION

1-Plasma TSH is the first investigation of choice  in a patient with suspected thyroid diease.

This may be mildly elevated in mild or subclinical hypothyroidism

TSH levels may be suppressed  in hyperthyroidism.

The anterior pituitary is very sensitive to minor changes in thyroid hormone levels which is why TSH is usually considered to be the most reliable investigation of thyroid function. 

2- Plasma free T4- confirms the diagnosis and assesses the severity of hyperthyroidism.  It is also used to diagnose secondary hypothyroidism. 

Both TSH and free T3 and T4 levels should be considered as it may be misleading in patients suffering from any pituitary disease. 

Eg: TSH may be normal or low in secondary hypothyroidism 

Raised T4 and T3 levels may be seen in initial stage of levothyroxine therapy. 

Other investigations may include measurement of antibodies against TSH receptors or other Thyroid antigens 

For instance: Antibodies to TPO, Thyroglobulin, TSH Receptor.

Some drugs may affect TFTs. For example: amiodarone may cause a decrease in free T4 and elevation of TSH. Amiodarone may also cause a decrease in TSH  causing hyperthyroidism in certain patients.

-Rudrani

Mitral valve anatomy and types of mitral regurgitation mnemonic

Mnemonic:

Prolapse tip points towards LV

Flail tip flips away from LV

Secondary stay away from each other (dilation) 

Job's syndrome

Job's syndrome is also known as hyper- IgE syndrome.

It has autosomal dominant inheritance ( STAT3 gene).

Here is the mnemonic to remember its key features :

A - Abscesses of face and lungs by staphylococcus aureus ( pneumatocele)

B - Bone fragility

C - Coarse facies

D - Dermatological features like eczema.

E - Eosinophilia, increased Ig E.

Trick to remember important points: 

"Steve Jobs is a dominant person, interested in business STATs"

That's all!

Dr. Madhuri.

Metoprolol tartrate vs succinate dosing mnemonic

Metoprolol tartrate is short acting. 

Metoprolol succinate is long acting. 

Mnemonic succinate single dose, tartrate two doses.

-IkaN (Nakeya Dewaswala Bhopalwala)