Complete drug profile of Levodopa

1. CLINICAL PHARMACY PRESENTATION
TOPIC : DRUG PROFILE OF LEVODOPA
SUBMITTED BY : MOHNI RASHEED (87-M-13)
MEHAK FARHEEN (85-M-12)
SUBMITTED TO : SIR ABDUL MAJEED Sb.

2. LEVODOPA
Generic Name : LEVODOPA
. The naturally occurring form of dihydroxyphenylalanine
and the immediate precursor of dopamine.
. Unlike dopamine itself, it can be taken orally and
crosses the blood-brain barrier. It is rapidly taken up by
dopaminergic neurons and converted to dopamine.
. It is used for the treatment of Parkinsonian disorders and is
usually given with agents that inhibit its conversion to
dopamine outside of the central nervous system.

4. PRODUCT DESCRIPTION

5. PRODUCT DESCRIPTION

7. CHEMISTRY OF LEVODOPA
• Chemical Formula C9H11NO4
IUPAC Name : 2-amino-3-(3,4
dihydroxyphenyl) propanoic acid
Structure :

8. PHYSICAL PROPERTIES
• COLOUR : Colorless to white crystals or crystalline powder.
ODOUR : Odourless
TASTE : Tasteless
MELTING POINT : 284-286 °C
SOLUBILITY : Readily soluble in dilute hydrochloric and
formic acids; practically insoluble in ethanol, benzene,
chloroform, ethyl acetate.
STABILITY : In presence of moisture , rapidly oxidized by
atmospheric oxygen & darkens.
pKa : 2.32 (at 25 °C)

9. PHARMACOKINETICS
• Absorption : Orally absorbed 64%
Distribution : Plasma Protein Binding = 36%
Plasma peak level in 0.5-2 hours.
Metabolism : Metabolized by decarboxylase
in GIT and blood vessels.
Excretion : Excreted unchanged in urine
Renal Excretion : 30%
Half Life : 2-3 hours

10. PHARMACODYNAMICS
• Mode Of Action :
Levodopa crosses BBB, where
it is converted to Dopamine. Only 1-3% Levodopa
actually enters brain unaltered. Addition of
Carbidopa lowers the dose requirement of
Levodopa, reduces peripheral side effects
associated with Levodopa alone.
Two forms are available :
1. 1:4 Levodopa 100mg , Carbidopa 25mg
2. 1:10 Levodopa 250mg, Carbidopa 25mg
.. Therapy is started with smaller dose. Dose is
raised gradually. Dopamine agonist can be added.

13. CLINICAL PHAMACOLOGY
PHARMACOLOGICAL CLASS : Central Nervous
System Agents.
RECEPTORS :
. Dopaminergic receptors (mainly)
. B- adrenergic receptors (tachycardia)
. Vascular adrenergic receptor stimulation (but
there is no rise in B.P)
. CTZ (elicits nausea+vomiting)
. Endocrine receptors (inhibit prolactin release by
mamotropes) , (increase growth hormone release
by somatotropes)
FDA PREGNANCY CATEGORY : “ C “

14. • INDICTAIONS : Parkinsonism & restless leg syndrome.
CONTRAINDICATIONS :
. In narrow angle glaucoma patients
. Respiratory disease
. Heart diseases
. Malignant melanoma
. Don’t use MAO inhibitors concomitantly
SIDE EFFECTS :
1. SERIOUS ONES :
. Postural hypotension
. Cardiac arrythmias
. Depression

15. . Seizures
. Exacerbation of angina
2. LESS SERIOUS ONES :
. Constipation
. Dry mouth
. Blurred vision
. Dizziness
. Darkening of urine and sweat
. Urinary retention

16. • PRECAUTIONS :
. Don’t take Levodopa if you’ve taken MAO
inhibitors.
. Narrow angle glaucoma
. Liver disease
. Kidney
. Asthma , COPD
. Stomach & intestinal ulcer
DOSE ADJUSTMENT IS REQUIRED IN THESE
CONDITIONS.

17. DOSAGE SCHEDULE
INITIAL DOSE : 250-500 mg orally B.D
MAINTENANCE DOSE : 3000-6000 mg per day in three
or more divided doses.
For RL Syndrome : 50 mg orally One to two hours
before bed time with decarboxylase inhibitor.
Take each dose with full glass of water, usually it is
taken several times a day with food.
PATIENT CARE CONSIDERATION :
Your doctor may want you to have blood tests or other
medical evaluations during treatment with levodopa to
monitor progress and side effects.

18. IF YOU MISS A DOSE , take the missed does as soon as
you remember, however it is almost time for the next
dose , skip the missed dose and only take the next
regularly scheduled dose.
Don’t take double dose of this medication.
INTERACTIONS :
. MAOIs in past 2 weeks
. Antacids
. Antihypertensive drugs
. Anti-seizures
. Papaverine
. Pyridoxine or Vit B6
. CCB , B-blockers, Diuretics

19. LEVODOPA – MAOIs
SIGNIFICANCE : 1
ONSET : Rapid
SEVERITY : Major
DOCUMENTATION : Established
EFFECTS : Hypertensive reactions.
MECHANISM : Inhibited peripheral
metabolism of LEVODOPA- derived Dopamine
with increased levels at dopamine receptors.
MANAGEMENT : Do not co administer. Or use
Selegiline, MAO type B inhibitor, do not
produces hypertensive reactions.

20. LEVODOPA – PYRIDOXINE
SIGNIFICANCE : 2
ONSET : Rapid
SEVERITY : Moderate
DOCUMENTATION : Established
EFFECTS : Reduces the effectiveness of Levodopa.
MECHANISM : Pyridoxine increases the peripheral
metabolism of Levodopa. Lower levels are available
for penetration into CNS.
MANAGEMENT : The interaction is of importance in
patients treated with Levodopa alone. Avoid giving
Pyridoxine. In patients taking levodopa/carbidopa
(e.g. Sinemet) combinations, the effect of
Pyridoxine is minimal to negligible.

21. TOXICOLOGY
OVERDOSE : Seek emergency medical
attention ; irregular heartbeat , muscle spasm
, convulsions occurs.
STORAGE
. At room temperature.
. Store in a tightly closed container.
. Away from high heat, moisture & light.
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