Preoperative Oral Heptaminol Hydrochloride in Preventing Hypotension After Spinal Anesthesia

heptaminol hydrochloride will be administrated in its solution form 4ml/kg. The mean dose used will be 25 drops = 150 mg and will be given 1.5 to 2 hours before spinal anesthesia

Placebo drops (identical to heptaminol drops, prepared by the hospital pharmacy) will be administered 1.5 to 2 hours before spinal anesthesia.